To fully understand this issue, you need to go from afar. Consider what oils are generally used in cars, how they fundamentally differ. Without going into details, these are engine oils, transmission (gear) oils, hydraulic booster oils, ATF and brake fluid. The similarity of all these oils, firstly, is that they are based on hydrocarbons obtained by processing fossil hydrocarbon raw materials, which accordingly gives some similarity in properties. All of them have a lubricating effect that increases slip between rubbing surfaces and a hydrorobic (repelling down) effect, as well as the ability to remove heat. A bit similar in appearance: oily to the touch with similar ones in the first approximation, this is where the similarity in properties ends.
This sometimes gives rise to irreparable errors when, for example, engine oil is poured into an automatic transmission, and brake fluid is poured into a hydraulic booster. Naturally, these actions are immediately followed by a breakdown of the unit. So how does ATF (Automatic Transmission Fluid) globally differ from all other substances poured into car devices.
ATF Properties
The fact is that ATF is the most complex fluid in a car, which requires a number of properties that sometimes contradict each other.
- Lubricating effect: reduced friction and wear in bearings, bushings, gears, pistons, solenoid valves.
- Increase (modification) of friction forces in friction groups: reduction of slippage (shift) between clutch pack frictions, brake bands, torque converter blocking.
- Heat removal: rapid removal of heat from the friction zone due to thermal conductivity and fluidity.
- Foam suppression: no foaming in air contact areas.
- Stability: no oxidation when heated to a high temperature and in contact with atmospheric oxygen for the longest possible time.
- Corrosion resistance: prevention of corrosion formation on the internal parts of the automatic transmission.
- Hydrophobicity: the ability to expel moisture from serviced surfaces.
- Fluidity and hydraulic properties: the ability to maintain stable fluidity and hydraulic properties (degree of compression) in a wide temperature range from -50 C to +200 C.
So what should be poured into the automatic transmission and how to top up ATF if the required ATF brand is not at hand or it is generally unknown what is filled in the automatic transmission?
To simplify the answer, we first make a few assertions.
- Any type of ATF - mineral water, semi-synthetics or pure synthetics are mixed together without any negative consequences. More modern ATFs have better performance and properties.
- The addition of a more modern type of ATF to a less modern type improves its properties.
- The less modern ATF, the worse its properties and therefore it must be changed more often, but even the most dense ATF of the DEXTRON II type will work with the most modern automatic transmission of the ZF6HPZ6 type without any problems. Proven in practice!
- No manufacturer discloses complete information about the composition and properties of the ATF they produce, limiting themselves to general advertising recommendations. The exception is special highly modified oils, in which their manufacturers do not know what they have mixed and promise a fantastic effect. Such liquids, if there is a desire to use them, are best poured without mixing with anything, since the effect is unpredictable.
- Manufacturers' guidelines for the use of ATF in their products are largely driven by the goal of increasing profits and are not always technically justified.
- It is desirable (but not necessary) to use ATF with constant frictional properties for automatic transmissions with hard torque converter lock-ups, and ATF with variable functional properties for automatic transmissions with mains lock-up having a controlled slip mode, the rest is not important.
- All pieces of iron, gears, bearings, clutches, seals, etc. in automatic transmissions they consist of materials of the same properties, regardless of the manufacturer of the automatic transmission, the nuances are not very significant, which means that different ATFs cannot have fundamentally different properties.
Summarizing all of the above, we draw the following conclusion: if you fill or change ATF in an automatic transmission as a whole, it is advisable to use a more modern and apparently more expensive ATF, taking into account only its frictional properties (variable or constant) for your automatic transmission. If the budget is limited, then you can fill in any ATF that is suitable for the price - this will not noticeably affect the operation of the automatic transmission, but the ATF will have to be replaced more often. Manufacturers' recommendations can be ignored at all. When pouring ATF into an existing liquid, if the same brand is not available, it is necessary to use a liquid with a class not lower than the main one, i.e. DEXTRON III. It is possible to add DEXTRON II, but vice versa, it is undesirable, because if you reduce the properties of ATF in the original automatic transmission, it may start to work worse, if you don’t know what is filled in at all and are afraid to do harm, add the most expensive modern ATF type DIV-DVI, again in friction properties.
ATF Composition
Due to the need to obtain such a large number of multidirectional properties, the composition of ATF is extremely complex and is not disclosed in detail by the Manufacturers. In open information, there are only general data on the chemical and molecular composition of the main additives, it is these additives (additives) that ultimately form the set of properties that ATF should have, detailed formulas of substances and their interactions are classified.
The chemical composition of ATF consists of two main parts - this is the base base and the additive package. The base base is the directly carrier fluid that makes up the main volume. According to its type, the base is divided into three main groups: mineral, semi-synthetic and synthetic. A mixture of mineral and synthetic bases is also used, which is sold as synthetic. Mineral bases include paraffinic (paraffinics) and naphthenic oils, their group in the classification systems XHVIYAPI ATIEL (the tehnical association of the european lubricans american petrolen Institute). Semi-synthetic or conditionally synthetic include hydrated (hidroisomerised) mineral base oils, which are considered improved, but relative to the first group, their VHVI classification, one of the Yubase brand names. But the true synthetic base group is the polyalphaolefin HVHVI (PAD) oils. The technology for their production is extremely complex and expensive at the moment, and in most cases commercially available synthetic ATFs consist of part of a synthetic base with the addition of a mineral or conditionally synthetic base component, which you will never be notified on the packaging.
GATF additives
The second part of the chemical composition of ATF is the additive package. Their chemical composition is also classified by manufacturers, and there is information in the public domain about the general chemical composition and percentage of ions of various substances: phosphorus - P +, zinc - Zn +, boron - Bo, barium - Ba, sulfur - S, Nitrogen, Magnesium, and etc.
In fact, these ions are part of polyesters, which in the mixture create additional chemical compounds, enhancing certain properties of additives.
That is why we are always talking about an additive package with certain characteristics.
Consider the ionic composition of the additive package of the most common DEXTRON III / MERCON ATFs. The total amount of additives in DIII in relation to the base oil is 17%, of which in the composition of ionizers:
- Phosphorus - 0.3% AW in 2-ethyl-hexyl-phosphoric acid, improves anti-wear properties in the ZDDP additive.
- Zinc - 0.23% as part of ZDDP zinc diethyl dithiophosphate - antioxidant properties, anti-wear.
- Nitrogen - 0.9% AW additive (Anti-Wear)
- Boron - 0.16% AW additive, enhances cleaning properties by enhancing ZDDP.
- Calcium - 0.05%, in the composition of calcium phenolates - a washing effect, plus a dispersant in the composition of the base additive TBN, anti-corrosion effect.
- Magnesium - 0.05% detergent properties as part of the base additive, acidity reduction, anti-corrosion effect.
- Sulfur - 0.55% AW additive, plus in the composition of friction modifiers (FM), anti-wear properties in the composition of EP.
- Barium - various%, control partial late.
- Siloxane - 0.005% active defoamer.
The following ions are part of additives that have complex formulas, the details of which are classified, some of their names and the general chemical formula:
- ZDP - zinc phosphate, anti-corrosion effect
- ZDDP - - dithio-phosphate, antioxidant, anti-corrosion.
- TCP - tricresyl phosphate, heat resistance enhancement.
- HP - chlorinated paraffin, high temperature resistance.
- MOG - glycerin monoplast
- Stearic acid
- PTFE - Teflon (almost never used in ATF)
- SO - sulfated EP (Extrime Pressure Additive) stabilizes properties under excess pressure.
- ZCO - zinc carboxylate, corrosion inhibitor.
- NA is a group of alkylated benzenes.
- POE - ethers.
- TMP – lineoleic ether polynols
- MODTP
In total, about a hundred such additives have been developed, and one package of additives can include up to 20 complex substances that, when combined, give a cross effect that creates the desired characteristics for ATF.
History of ATF creation
Experiments on the creation of automatic transmissions began in droves in the 20s of the 20th century, but in those days no one seriously thought about changing the properties of the hydraulic fluids used in them. The first big breakthrough came in 1949, when General Motors introduced the world's first serial development of ATF, designated Type A. It was based on petroleum mineral oil, and sperm whale spermaceti was used as the only additive. Sperm oil was secreted from the unfortunate animal by a special gland and accumulated in two bags located in the depressions between the bones in the upper part of the skull. These sacs served as resonators for the whale's ultrasonic signals. After killing and butchering the whale, the spermaceti fat was frozen from the contents of the spermaceti sacs and hydrated, resulting in a substance called Cetin, the chemical formula of which is C15H31COOC16H33, which was used as the main component of the first ATF.
The quality of ATF Type A turned out to be so high that the mixture practically did not require any modifications, based on the fact that at that time the transmissions were low-speed, and the operating temperature did not exceed 70-90 C. Over time, the power and torque increased, and the original Type A ceased to meet the requirements, as it oxidized at higher temperatures and foamed, unable to withstand high speeds.
The next in the development of ATF was the Type A Suffix A fluid created in 1957 with improved performance. For the first time, additives containing substances based on phosphorus, zinc and sulfur began to be used in minimal amounts (about 6.2%), which made it possible to improve the antioxidant and other properties of ATF.
After that, there was nothing new for ten years, and only in 1967 GM took the next step by creating ATF with index B. From that moment on, a classification called DEXTRON was introduced, and the liquid was called DEXTRON B. Its fundamental difference was that that a significant amount (about 9%) of substances based on barium, zinc, phosphorus, sulfur, calcium and boron was introduced into its composition, which can be called an additive package.
Unlimited chemical harvesting of whales brought them to the brink of extinction, and in 1972 the US government was forced to pass the Endangered Species of Animals and Birds Act, completely prohibiting whale hunting. ATF manufacturers have begun to have dark days. For several years it was not possible to find a replacement for spermaceti fat. When using the fluids left at the disposal of manufacturers, the number of automatic transmission failures increased 8 times in the United States, and the matter smelled like a disaster. It wasn't until the mid-1970s that International Lubricants, in collaboration with renowned organic chemist Philippe, developed a liquid synthetic wax ester called LIQUID WAXESTER, patented under the trademark LXE®, which made it possible to improve the required properties of ATF by an average of 50%. The resulting liquids even began to surpass ATF based on spermaceti in a number of characteristics. Based on this technology, in 1975 GM created DEXTRON II index C with an additive content of 10.5%. But it soon became clear that ATF turned out to be quite aggressive and began to cause corrosion of metal surfaces, so a year later DEXTRON II index D was created, which included additional corrosion suppressant additives. The next step in 1990 was DEXTRON II index E, which included viscosity stabilizers at low temperatures and stabilizers at high temperatures. In 1995, DEXTRON III became the crowning achievement of all creations, as part of which all modern requirements were taken into account and a complex package of additives was introduced. So far, GM has created the DEXTRON IV, DEXTRON V, and DEXTRON VI. In parallel with GM, in-house developers led a number of firms, such as Ford, who created a number of their own ATFs, united by the MERCON classification, Toyota's Tyret classification (DTT).
This led to a fair amount of confusion in the classification of oils and understanding their compatibility with each other and with the design of the automatic transmission. Therefore, over time, it was decided to tie all these standards to the GM-DEXTRON classification. Therefore, on most ATF packages of any company, you can see the inscription on the back of the annotation: “Analogue DEXTRON III” or “DIV”, etc.
What is the difference in the properties of ATF from different manufacturers. Determination of compatibility with the automatic transmission design.
I would like to note right away, no matter what worthy experts say, there is no fundamental difference in the properties of the most modern ATFs. If you go into details, then two main factors are taken as the criteria for difference:
- Interaction of ATF with various types of friction materials.
- Various characteristics of friction coefficients in the clutch of friction clutches of frictional properties (variable and constant coefficient of friction).
On the first point: There are about a dozen manufacturers of friction materials in the world, such as Borg Warren, Alomatic, Alto and others, each of which develops its own original compositions. The basis is usually a specially treated cellulose fiber (friction cardboard), in which various synthetic resins are added as a binder, and soot, asbestos, various types of ceramics, bronze chips, fiber composites of the type * and carbon fiber. Accordingly, it is believed that the manufacturer of the automatic transmission selects the type of ATF for the friction material used, selecting the optimal value of the shear coefficient between the clutches at full contact in order to minimize heat generation in the clutch packs. However, regardless of the difference in the composition of friction clutches, all developers use the same chain, therefore, high-quality friction clutches from native companies do not differ much in properties, therefore they react similarly to different types of ATF.
On the second point: The engagement parameters of the friction elements of the automatic transmission are determined by the coefficient of friction. Friction, respectively, is of two types:
- sliding friction that occurs when the friction elements come into contact until they are fully engaged;
- static friction, when the clutches come into a state of full engagement and become motionless relative to each other.
In addition to the clutches in the brake and drive elements of the automatic transmission, there is also a torque converter lock-up clutch, which, when switching from a hydrodynamic (due to the compression of fluids between oppositely located blades) mode of transferring the main torque to a hard one (when the lock is fully pressed against the body and the H / TR works as usual clutch on mechanics) gets the same set of friction effects. However, in G / T modern automatic transmissions of 6 or more steps, an intermediate mode has appeared, called controlled slipping of the lock (FLU - Flex Lock Up) for smoother and more comfortable shifting, when the pressure regulator with a high switching frequency applies and turns off the pressure that controls the lock, keeping it on the verge of slipping. Accordingly, all types of ATF are divided into two classes: with constant friction properties (Type F, Type G) and variable friction properties (DEXTRON, MERCON, MOPAR).
ATF with unchanged frictional properties has a fairly linear picture: as the friction clutch is pressed (slip speed decreases), the friction coefficient increases, and at the moment the friction clutches engage, it reaches a maximum. This gives the effect of clearly working out gears with the allocation of minimal correspondence.
Accordingly, there is a sense of switching effect. When using ATF with variable friction properties, at the initial stage of pressing the friction clutch, the coefficient of friction-sliding has a maximum value, but as they are compressed, it decreases somewhat, reaching again a maximum at full contact, but at this value, the static friction coefficient is much lower. This gives the effect of smoother and more comfortable shifting, but the amount of heat generated increases.
Possible consequences: If you fill in ATF with variable properties in an automatic transmission with a hard inclusion of g / t, this can cause an undesirable effect of slipping the lock. In the case of an unworn automatic transmission, the hydrodynamic transmission will maintain torque until it is fully engaged and nothing unpleasant will happen. In a worn or damaged automatic transmission with burnt locks and clutches, excess slip can aggravate the situation and cause fatal destruction. If, however, in an automatic transmission with controlled slippage of the lock, fill in ATF with unchanged frictional properties, this can cause a harder gear shift, but will not bring tragic consequences. From this we can conclude that it is possible to add ATF with modified friction properties to it, and it will work softer, and if there is a feeling that the automatic transmission is slipping a little more than necessary, you can fill in ATF with unchanged friction properties and it will work more clearly.
In conclusion, I can add that much more serious factors than the friction properties of oils that affect the operation of automatic transmissions are temperature conditions, the degree of wear of friction clutch surfaces and other devices and control components, and frost. Before these factors, differences in ATF properties become negligible. It makes sense to take them into account only if there are ideal operating conditions for a new car.
The latest development on the ATF market
A few years ago, the technologists of the petrochemical company AMALIE MOTOR OIL developed a universal synthetic ATF, which has no analogues in the world, has fantastic properties, which equally meets the requirements of all types of automatic transmissions. The fluid was called "Amalie Universal Synthetic Automatic Transmission Fluid", which made a real revolution in the US market, having received certification from all leading car and automatic transmission manufacturers. A new type of fully synthetic base and a state-of-the-art multifunctional additive package provide unsurpassed protection and stable performance when used in any type of automatic and robotic transmissions, hydraulic boosters and other hydraulic systems, regardless of manufacturer. It successfully replaces the entire line of DEXTRON, MERCON, transmission fluids from Chryster, Toyota, Caterpilar and other manufacturers. The fluid is recommended for use in heavily loaded automatic transmissions from manufacturers such as BMV, Audi, Land Rover, Mercedes, Mitsubishi, Toyota and any other vehicles of the American, European and Asian markets. Two years ago, this ATF appeared on the Russian market. For those car owners who have the means and do not spare them for the maintenance of their iron horses, this product is a real solution.
Clickable
We begin our review of topics that interest the readers of this blog and they order them at. Today we have a theme from blogcariba which is unlikely to be of interest to many, but perhaps our discussion in this post will help him. And that's what worries him "Right now I'm interested in the following question: the effect of universal ATF oil on the operation of the gearbox torque converter or why does it kick?))))))"
Let's start with a little history...
The first specification for ATF (Automatic Transmission Fluid - automatic transmission fluid) type "Dexron" was released by GM at the dawn of time, in 1967 (Dexron B). Further specifications are regularly updated:
1973 - Dexron II (DIIC), which became the de facto ATF worldwide standard.
1981 - Dexron IID - the one that we now understand under the brand name "dexron-2".
1991 - Dexron IIE - improved specification, synthetic based ATF (as opposed to mineral DIID), has better viscosity-temperature properties.
1993 - Dexron III (DIIIF) with new requirements for friction and viscosity properties, remains the standard to this day.
1999 - Dexron IV (synthetic base)
Ford also tried to keep up with GM with its "Mercon" specification, but, despite more frequent updates (or maybe because of this), it did not receive such distribution and ATF Mercon (at least until recently) is officially completely unified with Dexron "ohm (for example - DIII / MerconV).
The remaining member of the "big three", Chrysler, went its own way with Mopar's ATF (until the mid-90s - 7176 or ATF +, more recently - 9xxx). It is from him that you can count the beginning of the struggle of special ATF for existence. Although sometimes Chrysler makes life easier for users with a simple recommendation: "Dexron II or Mopar 7176" (this is a word about interchangeability).
The Mitsubishi (MMS) - Hyundai - Proton conglomerate, now associated with Chrysler, went the same way. In the Asian market, they use the MMC ATF SP specification (from Diamond), and Hyundai - and their proprietary (genuine) ATF, the essence is the same SP. On models for the American market, SP is replaced by Mopar 7176. If we talk about grades, then ATF Diamond SP is mineral water, SPII is semi-synthetic, SPIII is apparently synthetic. Euroanalogues are especially successful in BP (Autran SP), so you can see more in their company catalogs. By the way, it was repeatedly categorically written that "only special ATF SP can be poured into MMC machines." This is not entirely true. Many old MMC automatic boxes are prescribed to be filled with Dexron "a. Approximately, this can be defined as follows: automatic transmissions of all (or almost all) families, produced until about the period 1992-1995, were refueled with DII, automatic transmissions from 1992-1995 - already ATF SP, then from 1995-1997 - SP II, current automatic transmissions - SPIII. So the type of fluid to be filled should always be specified according to the instructions. Otherwise, the same principles apply to ATF SP as described below for ATF Type T ( Toyota).
And finally, actually Toyota. Its fluid - Type T (TT) originates in the 80s and is used in A241H and A540H all-wheel drive boxes. The second type of special fluid, Type T-II, designed for electronically controlled boxes and FLU, appeared in the early 90s. In the 95-98th years. it was replaced by the TT-III and later by the TT-IV.
Do not confuse "just Type T" (08886-00405) with TT-II..IV - in the language of lovers of original fluids, "these are ATFs with different properties."
The synthetic Castrol Transmax Z (which, by the way, is extremely close to DIII) was officially recognized as the Euroanalogue of the first Type T, Mobil ATF 3309 is now considered as an analogue of Type T-IV. In general, due to periodic changes in recommendations (even for the same generation of the model ) the nominal type of ATF should be specified in the native instruction manuals - it depends not only on the type of box, but also on the year of manufacture of a particular car.
Why does the manufacturer need it?
On the one hand, how much easier it would be for the mentioned auto giants not to invent a bicycle, but to use the most massive ATF (by the way, Europeans mainly follow this path), but on the other hand, why not feed affiliated oil producers? Since Dexron can now be produced by anyone who is too lazy, and GM should receive a "kickback" for certification, then the Japanese, who can count no worse than the rest, wanted their share of the profits. Fortunately, no one bothers them to introduce new specifications, but the owners will still have to pay for it. Yes, and competent positioning allows you to convince people that TT and other special ATFs are much better than Dexron's. And pay attention - it is often written on Dexron "e" - "do not use instead of Mopar, SP, etc.", but on many special ATFs - something like "it is acceptable to use in automatic transmissions for which Dexron is recommended." So, at the same time, special oilers are not afraid of any mechanical problems with "ordinary" automatic machines - the main thing is to increase sales. Is it possible vice versa?
Why does the box need it?
And really, what was all this trouble for? Indeed, according to the viscosity-temperature properties for any of the special ATFs, an analogue from Dexron's is easily selected. So it turns out that the only difference between special ATFs is the presence of some "increased frictional properties" (i.e. they increase friction).
For what? Since in these automatic boxes the torque converter mode is provided with "partial blocking" (FLU - Flex Lock Up). Simplified, it is implemented as follows. A conventional automatic machine operates in two modes - either as a torque converter (GDT), transmitting torque through a liquid, or in a hard blocking mode, when the engine crankshaft, the gas turbine housing and the input shaft of the box are rigidly connected by a friction clutch and the moment is transmitted to the automatic machine purely mechanically, without loss ( as in a traditional clutch). In a box with partial blocking, there is also an intermediate mode, when the transformer blocking valve is activated at high frequency, briefly bringing and retracting the clutch to the GDT body in order to transfer force through it at the moment of contact. That's practically all. If at the same time, for some reason, there is not enough friction force to transmit torque through the clutch, then the box will still work - in normal hydraulic transmission mode. Of the most unpleasant consequences that can be expected - a slightly increased fuel consumption and a slightly lower engine braking efficiency (and even then, not necessarily). Could there be mechanical damage? Why would it be - the box will work out this mode one way or another, regardless of the efficiency of rotation transmission, and secondly, there is also feedback (speed sensor of the gearbox input shaft), which will allow you to adjust the FLU control signal. Yes, and partial blocking is implemented at low loads on the engine (for example, at forced idle) and in a rather narrow speed range.
We will especially note the "all-wheel drive machines", including far from new ones - why do they need TT? They just use a hydromechanical clutch for automatic locking of the center differential, which is similar in principle to FLU (only multi-plate).
If for a new box in ideal Japanese conditions the ATF characteristics will have some influence on the work, then in those machines that work with us, completely different factors will be decisive. Think for yourself what will turn out to be stronger - a slightly modified composition of the liquid (not so much modified as "having fixed properties", and then only according to the manufacturer. By the way, how much more can this friction coefficient be? After all, do not forget that in that ATF itself bathes not only the lock-up clutch, but also the rest of the box clutches, and planetary gear sets that came from the basic versions of the same families of machines without FLU) or real ones:
- wear over time of the lock-up clutch or change in the properties of its clutch
- pressure of the working fluid (fluctuations of which by 10-15% of the average value are the norm for a new box)
- engine adjustments
- general wear of automatic transmission elements (both in the hydraulic part and in the mechanical part)
- automatic transmission adjustments (again, the spread of nominal values)
- driving style
- condition and aging of the filled ATF
- climatic conditions (especially frosts) ...
And let's not forget - boxes with FLU are not exclusive know-how of the Japanese, but the fact is little known that both Dexron III, and, moreover, Dexron IV were developed taking into account the requirements for automatic machines with partial blocking.
Due to the fact that a hydromechanical transmission (HMT) includes several different units (torque converter, gear box, complex automatic control system), more stringent requirements are imposed on the oil operating in it than on oil for mechanical gearboxes.
| Oil brand | Possible substitutes | Oil type, recommended application |
| TM-2-18 | TM-3-18 | Spur and worm gears; all-weather, workable up to -20˚С |
| TM-3-18 | TM-5-12V, TM-5-12rk | Spur, spiral bevel and worm gears; all-weather, workable up to -25˚С |
| TM-3-9 | TM-5-12V, TM-5-12rk | In vehicle transmission units at air temperatures up to -45˚С; all-weather for the northern regions, winter variety for the northern strip |
| TM-5-12 | - | All-weather for the cold climate zone and winter for the middle lane. The oil is universal. Temperature range of oil performance from -40˚С to 140˚С |
| TM-4-18 | TM-5-18, TM-5-12V, TM-5-12rk | Hypoid gears for trucks, all-weather for temperate climate zone, operable up to -30˚С |
| TM-5-18 | TM-5-12V, TM-5-12rk | Transmission units with hypoid gears, gearboxes and steering of passenger cars; all-weather, workable up to -30˚С |
| TM-4-9 | TM-5-12V, TM-5-12rk | Transmission units of automotive equipment, including those with hypoid main gears when operating in a cold climate zone up to a temperature of -50˚С |
Table 2.19. Consumer properties of additives and additives for gear oils
| Name of the drug | Purpose | Country, manufacturer |
| FenomMANUALTRANSMISSIONCONDITIONER F ENOM Series Manual Transmission Conditioner | Improving the performance of gearboxes, transfer cases and final drives of drive axles, including hypoid type | Russia, LT "Laboratory of Tribotechnology" |
| H.P.L.S. | Reduced wear and noise in manual transmissions, transfer cases and gearboxes | Belgium, Wynn's |
The main functions of oils in the GMF are: power transmission from the engine to the chassis of the car; lubrication of components and parts of the gearbox; circulation in the HMF control system; transfer of energy to turn on the friction clutches of the GMP; cooling of parts of units and mechanisms of the unit.
The average oil temperature in the GMP crankcase is 80-95 °C, and in the summer period during the urban driving cycle - up to 150 °C. Thus, HMF is the most heat-stressed of all vehicle transmission units. Such a high oil temperature in the HMF, in contrast to a mechanical gearbox, is created mainly due to internal friction (the oil flow rate in the torque converter reaches 80-100 m/s). In addition, if more power is removed from the engine than is necessary to overcome road resistance, the excess power is spent on internal friction of the oil, which further increases its temperature. High speeds of oil movement in the torque converter lead to its intense aeration, increased foaming, and accelerate oil oxidation.
The design features of the HMF impose stringent, sometimes conflicting requirements on the oil (for example, high density and low viscosity, low viscosity and high anti-wear properties, high anti-wear properties and fairly high frictional properties). The main physical, chemical and operational properties of domestically produced oils for hydromechanical transmissions are given in Table. 2.20.
To ensure the operation of the hydro-transformer with the highest efficiency and the reliable operation of the lubricated parts, the oil must have an optimal viscosity. An increase in the viscosity of the oil due to a decrease in its temperature from90 °C to 30 °C leads to a decrease in the efficiency of the hydro-transformer by an average of 5-7%. On the other hand, to provide a strong oil film on the friction surface and reduce leakage through sealing devices, the oil must be relatively viscous. The use of oils with a viscosity at a temperature of 100 ° C equal to 1.4 mm 2 / s instead of 5.1 mm 2 / s in the GMT improves the dynamic characteristics of the car by 6-8%, and also contributes to fuel economy. The highest efficiency of hydraulic transmissions is ensured when the oil viscosity is not higher than 4-5 mm 2 /s at a temperature of 100 °C.
The anti-wear requirements for the oil are also very high. A wide variety of materials for friction pairs (steel-steel, steel-cermet, etc.) used in GMT makes it difficult to select oils and additives to them. The presence of some additives in oils reduces the wear of ferrous metals, but causes great wear of non-ferrous metals, and sometimes vice versa.
In addition, for the normal operation of the friction discs, the oil must provide an increased coefficient of friction: from 0.1 to 0.18. When the friction coefficient is less than 0.1, the operation of the clutch discs is accompanied by slipping, and when the friction coefficient is greater than 0.18, it jerks. In both cases, this leads to premature failure of the friction discs. The antioxidant resistance of the oil ensures reliable and durable operation of the HMF. Oxidation of the oil, in addition to its general pollution and an increase in the content of acidic products, leads to a disruption in the normal operation of the friction discs.
Table 2.20. Characteristics of domestic oils for hydromechanical transmissions
| The name of indicators | General purpose for spur, bevel, helical bevel and worm gears | |
| A (for hydromechanical transmissions) | R(for hydrostatic transmissions) | |
| Kinematic viscosity, mm 2 / s: at 100˚С at 50˚С |
7,8 23-30 |
3,8 12-14 |
| Flash point, ˚С, not lower | 175 | 163 |
| Pour point, ˚С, not higher | -40 | -45 |
| Operation at temperature, ˚С, not lower than | -30 | -40 |
| Content of active elements, %: calcium phosphorus zinc chlorine sulfur total |
0,15-0,18 - 0,08-0,11 - - 0,23-0,29 |
0,15-0,18 - 0,08-0,11 - - 0,23-0,29 |
| SAE viscosity grade | 75W | - |
| API viscosity grade | GL-2 | GL-2 |
The high operating temperature of the oil in the HMF, direct contact with a large amount of air in the presence of catalytically active non-ferrous metals causes its rapid oxidation in volume, a thin layer and a misty state.
In addition, the design features of the HMF, as well as the operating conditions of the car, have a great influence on the oxidizability of the oil. So, for example, driving a car in city mode with frequent stops and low speeds causes faster oil oxidation than driving on country roads.
To reduce the intensity of oil oxidation and reduce the deposition of varnish and sludge on hydraulic transmission parts, antioxidant and detergent additives are added to oils. In addition, automatic transmissions are sometimes equipped with cooling systems.
The corrosive aggressiveness of the oil to various materials should be minimal, since the parts of the HMF are made of various metals and their alloys. Parts made on the basis of non-ferrous metals are most susceptible to corrosion.
The chemical composition of the oil must not have a harmful effect on rubber sealing devices, i.e. cause excessive swelling or shrinkage of rubber parts leading to oil leakage. The swelling of rubber parts should be no more than 1-6%.
Anti-corrosion additives are added to the oil to prevent corrosion of HMF parts.
The density of the oil is of great importance for the efficient operation of the GMF. The higher the density, the more power the hydro-transmission can transfer.
The density of the oil used in the HMF, at an operating temperature of 80-95 ° C, ranges from (81.8-80.9) 10 -6 n / mm 3, and at room temperature - (86.3-86.7 ) 10 -6 n/mm 3 .
The cooling properties of the oil are evaluated in terms of specific heat capacity, which for HMF in the operating temperature range should be 2.08-2.12 kJ / kg ° C.
The resistance of the oil to foaming is ensured by the addition of antifoam additives to it.
The quality of gear oils and an increase in their service life are achieved by introducing additives into their composition. In table. 2.21 shows the consumer properties of some additives and additives in gear oils for GMF in order to improve their performance properties.
According to GOST 17479.2-85, gear oils, depending on their performance properties, are divided into 5 groups that determine their areas of application (Table 2.22) and into 4 viscosity classes (Table 2.23).
Marking of gear oils, for example, TM-2-9, is carried out as follows: TM - gear oil; 2 - oil group according to operational properties; 9 - viscosity class.
Viscosity classes of gear oils in accordance with SAE are given in table. 2.24.
In accordance with the API classification, gear oils are classified according to the level of their anti-wear and extreme pressure properties. Oils of classes GL -1 are used at low pressures and sliding speeds in gears. They do not contain additives. GL-2 oils contain anti-wear additives, and GL-3 oils contain extreme pressure additives and ensure the operation of spiral bevel gears, including hypoid ones.
Table 2.21. Consumer properties of additives and additives to oils for automatic transmissions
| Name of the drug | Purpose | Country manufacturer |
| Automatic transmission and power | Ensuring smooth shifting and eliminating fluid leaks from the automatic transmission | Belgium, Wynn's |
| Tuning for Trans Extend With ER | Provides perfect operation of the automatic transmission, is used after 10 thousand kilometers of the car or after it has been parked for 3-4 months | USA Hi-Gear |
| Trans-Aid Conditioner & Sealer | Eliminate slippage, increase service life and stop fluid leakage | US, CD-2 |
| Sealant and Tuning for automatic transmission Trans Plus | Protects the transmission from overheating during operation, eliminates leaks from the box within 15 km of the car run, compatible with all types of automatic transmission fluids | USA Hi-Gear |
| Sealant and Tuning for automatic transmission Trans Plus With ER | Protects against overheating during operation, ensures perfect operation of the automatic transmission, eliminates leaks from the box for 15 km of the vehicle run, compatible with all types of fluids | USA Hi-Gear |
Oils of class GL-4 are used for medium-loaded hypoid gears and transmissions operating under conditions of extreme speeds and shock loads, as well as at high speeds and low torques or low speeds and high torques.
GL-5 class oils are used for highly loaded hypoid gears of passenger cars, as well as commercial ones equipped with transmissions operating in shock load modes at high speeds, and, in addition, in low torque modes at high speeds or high torques at low speeds. Approximate correspondence of gear oils according to viscosity classes and groups of operating conditions in accordance with GOST 17479.2-85, the SAE system and the API system are given in Table. 2.25.
Due to the specific requirements for oils for automatic hydraulic transmissions, these oils are sometimes called ATF fluids (Automatic Transmission Fluids).
The major manufacturers of hydromechanical transmissions have developed specifications for automatic transmission fluids. The most common requirements are General Motors and Ford.
General Motors classifications correspond to oils under the DEXRON brand (DEXRON II, DEXRON ME, DEXRON III).
Ford oils are designated by the MERCON brand (V 2 C 1380 CJ, M2C 166H).
Table 2.22. Groups of gear oils according to the content of additives, performance properties and their areas of application
| Oil group | Presence of additives in oil | Recommended area of application, contact stresses and oil temperature in the volume |
| 1 | Mineral oils without additives | Cylindrical, bevel and worm gears operating at contact stresses from 900 to 1600 MPa and oil temperature in the volume up to 90˚С |
| 2 | Mineral oils with antiwear additives | The same at contact stresses up to 2100 MPa and oil temperature in the volume up to 130˚С |
| 3 | Mineral oils with moderate EP additives | Cylindrical, bevel, spiral-bevel and hypoid gears operating at contact stresses up to 2500 MPa and oil temperature in the volume up to 150˚С |
| 4 | Mineral oils with high performance EP additives | Cylindrical, spiral-bevel and hypoid gears operating at contact stresses up to 3000 MPa and oil temperature in the volume up to 150˚С |
| 5 | Mineral oils with EP additives of high performance and multifunctional action, as well as universal oils | Hypoid gears operating with shock loads at contact stresses up to 3000 MPa and oil temperature in the volume up to 150˚С |
Table 2.23. Viscosity classes of gear oils in accordance with GOST 17479.2-85
| Viscosity class | Kinematic viscosity, mm 2 / s, at a temperature of +100˚С | Temperature, ˚С, at which the dynamic viscosity does not exceed 150 Pa s |
| 9 | 6,00-10,99 | -45 |
| 12 | 11,00-13,99 | -35 |
| 18 | 14,00-24,99 | -18 |
| 34 | 25,00-41,00 | - |
| Viscosity class | Temperature, ˚С, at which the viscosity does not exceed 150 Pa s, not higher | Viscosity, mm 2 / s, at a temperature of 99˚С | |
| min | max | ||
| 75W | -40 | 4,2 | - |
| 80W | -26 | 7,0 | - |
| 85W | -12 | 11,0 | - |
| 90 | - | 13,5 | ≤24,0 |
| 140 | - | 24,0 | ≤41,0 |
Table 2.25. Compliance with viscosity grades and groups of gear oils in terms of performance properties in accordance with GOST 17479.2-85, SAE and API systems
| GOST 17479.2-85 | SystemSAE | GOST 17479.2-85 | SystemAPI | Scope of application according to operating conditions |
| Viscosity class | Operating condition group | |||
| 9 | 75W | TM-1 | LG-1 | Gears using oils with depressant and antifoam additives |
| 12 | 80W/85W | TM-2 | LG-2 | Mechanisms using oils with antifriction additives |
| 18 | 90 | TM-3 | LG-3 | Omniscient axles with spiral bevel gears; weak extreme pressure additives |
| 34 | 140 | TM-4 | LG-4 | hypoid gears; medium strength EP additives |
| - | 250 | TM-5 | LG-5 | Hypoid gears for trucks and cars; active extreme pressure and antiwear additives |
| - | - | - | LG-6 | Hypoid gears operating in very difficult conditions; highly effective extreme pressure and antiwear additives |
I don't know what car blogcariba
but here is what people are saying:
As far as I understand (having studied the forums), "kicking" Nissan boxes are almost the norm. They say business class, but not the same.
Some manage to achieve smooth shifting by adjusting the brake band tension, accessible from the outside without disassembling the car. But this is rather an exception, and it's too early for me to climb into the wilds.
At first, he was surprised (if not more) by this circumstance. I noticed that the attitude to the replacement of fluids, to put it mildly, is not ice. It is not uncommon to mention the partial replacement of ATF in automatic transmissions after 40-80 thousand. Three years later on official services. They ride semi-synthetics for 10-12 thousand, and then they look for contract engines. The manufacturer's recommendations are practically ignored, and they are almost the same as for the Taurus.
In a word, I didn't like it.
Three weeks ago, Nippon ATF Synthetic was filled in, especially since Nissan Matic Fluid C, D, J (level) was declared. A week later, with a syringereplaced another 4 liters. Positive changes appeared immediately, and since yesterday the box stopped kicking. I thought it was an accident, in the morning I changed the dynamics of the ride - it does not kick. Let's see what will happen next. I won’t say that the switching is completely invisible, but there are no kicks for sure. If you do not know - completely invisible.
Gearbox oils are a separate group of oils. Automatic transmission oil has a higher viscosity, it uses completely different additive packages than engine oil. Higher requirements are imposed on such an oil in terms of its anti-wear, anti-friction and antioxidant properties, since the service life of the oil in an automatic transmission ranges from 30 - 40,000 km to the entire life of the car. The diverse tasks performed by oil in automatic transmissions place very high demands and restrictions on its properties. Oil cools, lubricates, provides frictional grip and transmits torque. The operating temperature range of oil in automatic transmissions is from 90°C to 150°C. Completely different materials used in automatic transmission friction pairs (steel - bronze, steel-cermet, steel - steel, steel - composite materials) cause the use of different packages of antifriction additives in the oil, which are not always compatible with each other. At the same time, it is necessary to prevent aeration, and as a result, foaming of the oil in the automatic transmission, which occurs when hot oil flows are swirled under pressure. The result of aeration and foaming of the oil is the oxidation of the oil and corrosion of the materials from which the automatic transmission is made. The automatic transmission is a highly loaded unit, during the operation of which part of the energy converted into translational motion is spent on the internal friction of the oil, which leads to its significant heating. As a result, the requirements for oil viscosity in automatic transmissions are opposite: to reduce the internal friction of the oil during the operation of the torque converter, the oil must have a low relative viscosity, and to ensure gear lubrication, on the contrary, the oil must have a sufficiently high viscosity.
Types of oil for automatic transmission.
Three main types of oils are used in automatic transmissions: Dexron, Mercon and MB. This is due to the historical specification for automatic transmission oil. The first oil specification was formulated in 1949 by GM Corporation. At the turn of 1990. the requirements of different specifications have become almost the same so much so that all gearbox oils have become interchangeable. Dexron IV oils are designed for use in automatic transmissions with an electronically controlled torque converter clutch.
GM automatic transmission oil specifications (GENERAL MOTORS)
GM first faced the need to develop and formulate separate specifications for the classification of automatic transmission fluids (Automatic Transmission Fluids - ATF, another name for automatic transmission oil).
ATF type A refers to a type of gear oil that is suitable for automatic transmissions in passenger cars. Oils that passed the tests received AQ qualification numbers. Qualification numbers AQ were assigned under an agreement with GM research center "Amour Research" in the format "Amour Qualification N". Specifications have lost their relevance.
DEXRON (B) - current and current specifications for automatic transmission fluids (automatic transmission oils) GM. Many manufacturers or buyers of such automatic transmissions also use these specifications. The approval is made under the so-called type "B".
DEXRON II, III, IV are the latest specifications for GM oils (automatic fluids). They tighten the requirements for fluids for automatic transmissions. They include and exceed all previous specifications, meet the increased requirements for ensuring environmental safety. Allison Fluids: Type C1 and Type C2 specifications superseded by DEXRON II specifications; "type SZ" - MIL-L-2104D.
FORD Specifications
"Type F" automatic transmission fluids, according to the latest Ford M2C33F and M2C33G specifications, differ significantly from DEXRON oils in some parameters (for example, friction coefficient). The main difference is in the coefficient of friction, which in the case of Ford increases with a decrease in sliding speed, while General Motors, on the contrary, requires a decrease in the coefficient of friction in the same case.
ATF type automatic transmission fluids according to Ford M2C138-CJ and M2C166H specifications can be partially replaced with DEXRON II fluids, however, a complete automatic transmission oil change is most preferable.
Fluids for automatic transmissions of the ATF Dexron II, Plus Dexron III and ATF-A series are designed for transmissions operating under conditions of high mechanical and thermal loads, can be used in transmissions of passenger cars of any automaker, hydraulic power steering and clutch units. Fluids for automatic transmissions of the ATF group are produced under two brands: ATF II D Plus and Dexron III. ATF II D Plus is designed to work in highly loaded transmissions, belongs to the Extrimal Pressure category (extreme pressure). A balanced high-tech additive package provides high anti-corrosion properties. In terms of its parameters, this automatic transmission oil meets the requirements of most of the world's leading automakers. Dexron III is used in automatic transmissions of passenger cars, light commercial vehicles and minivans.
Other specifications.
In addition to the specifications of General Motors and Ford for automatic transmissions, the factory specifications of Chrysler, MAN, Toyota, Allison, Renk, Voith, ZF are used. For vehicles sold in Europe with automatic transmissions manufactured by ZF, automatic transmission oils are selected according to GM specifications. In the automatic transmissions of Audi, BMW and Mercedes of the last years of production, only synthetic automatic transmission oil is poured!
Oil change in automatic transmission.
Changing the oil in the automatic transmission must be carried out in strict accordance with the operating instructions for your car! Violation of oil change intervals, as a rule, leads to a sharp deterioration in the functionality of the automatic transmission and a reduction in its service life. Under severe vehicle operating conditions (driving with a full load, driving with a trailer, frequent engine braking, using vehicles on roads with dirt, sand and snow, high or low ambient temperatures, wheel slip, using the vehicle in start-stop mode (urban traffic jams ), sharp acceleration from a standstill - all automakers recommend reducing the oil change intervals in the gearbox by half. In practice, this leads to a reduction in the service interval for automatic transmission oil in Moscow to 30, maximum 40,000 km! Change the oil more often - your automatic transmission will last longer!
Mixing automatic transmission oils of different types when replacing them.
Mixing is possible, well, it's best to avoid it. To quickly identify the oil poured into the automatic transmission, a dye is added to the oil, the addition of which does not lead to a change in the properties of the oil. However, in conditions where you cannot clearly identify the previously filled oil, it is highly recommended to carry out a complete automatic transmission oil change. The cost of even the smallest repair of an automatic transmission is ten times higher than the cost of a complete oil change in an automatic transmission.
Non-original automatic transmission oil for your car.
When changing the oil in automatic transmissions, some automakers, such as Honda and Mitsubishi, require the use of specialized oils under their brands. It must be understood that neither Honda nor Mitsubishi produce oil on their own, but order its production from leading petrochemical corporations (ExxonMobil, BP, Chevron, PetroCanada, and so on). In addition, information has recently appeared in the press that automakers began to place orders for engine and transmission oils poured into engine units on the conveyor at private factories in Europe (Ravenol, Addinol, and so on) according to their specifications. At the same time, transmission and engine oils produced by Ravenol under its own brand for use in cars, for example, Hyundai and KIA, for the most part of their performance surpass oils produced by the same Ravenol, but distributed in packaging and under the Hyundai brand - the automaker saves money and is not interested in order for the car to work without breakdowns and after the expiration of the warranty period. Therefore, according to experts, the use of oils produced by private European factories directly for use in automatic transmissions of cars of a particular car manufacturer is the best option for those car owners whose warranty period for cars has already expired.
Do I need to change the fluid in an automatic transmission?
If you believe the operating instructions, then in the case of a new car, the “automatic” does not require any maintenance up to a mileage of 100 thousand kilometers. True, oiler skeptics frown: they say, by 40-50 thousand it would be nice to fill in fresh ATF (Automatic Transmission Fluid), suitable for a particular machine. But along with specialized fluids, the so-called “cartoons” are also popular - ATF with the beautiful name Multi-Vehicle (“multi-weekle”, that is, for different cars), which can be poured into almost any automatic transmission without bothering to look for a branded oils.
It would seem, why are they needed if you can buy your own liquid? The answer is simple: for the secondary. They are taken by those who are already on the second circle of the odometer riding the "machine" and have no idea what and when it was poured. In addition, not every warehouse or store keeps a bottle in its bins that is obviously suitable for your AT. The supply of liquid under the order can take a long time - and the "cartoons" correspond to many tolerances. So the question here is not at all in the price (“cartoons” are not cheaper), but in the speed of solving the problem.
In general, for the test, we took eight liquids with the designation Multi-Vehicle. Checking the "cartoons" seemed very interesting to us, because from a technical point of view, creating such a product is very difficult. It is clear that it is an impossible task to evaluate their versatility in full: the number of requirements, approvals and specifications for ATF exceeds a hundred (both car manufacturers and gearbox manufacturers are trying). Therefore, we have combined all kinds of criteria into groups that are closer and more understandable to the consumer.
Here are the parameters by which we will check them.
1. Friction losses in the gearbox. I wonder if the driver will feel the difference or not?
2. Influence of fluid on the efficiency of energy transfer from the engine to the transmission. Dynamics and fuel consumption depend on this.
3. Cold start.
4. Protective properties of the liquid. By the rate of wear of friction pairs, we will estimate the proximity of repair or, God forbid, replacement of the box.
HOW WE CHECK
The main physical and chemical indicators - viscosity and viscosity index, flash point and pour point - we measured in a certified laboratory. Friction losses and wear were evaluated on a friction machine - a device that simulates the operating conditions of various friction pairs. The tests were carried out in two stages. At the first stage, a model similar to gearing was investigated. At the second stage, the operating conditions in the bearings were simulated. At the same time, friction coefficients, oil heating, wear of friction pairs were measured. Wear was determined by accurate weighing of parts before and after the test cycle, and for the bearing model - also by the method of holes. This is when, before testing, a hole of a fixed size is cut on the working surface of the sample, in the zone most subject to wear, and at the end of the test, a change in its diameter is recorded. The more it increases, the higher the wear.
Tests for each liquid at one stage and another lasted a long time: one hundred thousand load cycles for the bearing model and fifty thousand for the gear model.
DISTRIBUTION OF gingerbread
So, let's see what happened. It immediately caught my eye that the effect of the brand of liquid on the coefficient of friction was very ambiguous. For the gearing model, all differences were within the limits of the measurement error. The Dutch NGN Universal ATF looks a little better than others. But for the bearing model, everything is different - the run-up of the measured parameter is quite large. Here the best performance is for Motul Multi ATF and Castrol ATF Multivehicle fluids.
How critical is the difference in this parameter? On the scale of the entire power unit (engine and gearbox), the proportion of friction losses in the box is not so large (if we do not take into account losses in the torque converter). On the other hand, oil heating due to friction when operating on different fluids differs much more significantly: the average cumulative difference for the gear and bearing models is approximately 17%. From the point of view of the temperature effect, this difference is very noticeable - up to 10–15 degrees, which give a change in the efficiency of the torque converter by noticeable units of percent. Motul synthetics look better than others here. Only slightly inferior to her liquid NGN Universal and Totachi Multi-Vehicle ATF.
The heating of the liquid also affects its viscosity: the greater the heating, the lower it is. And with a drop in viscosity, the efficiency of the torque converter decreases. Many people remember problems with “automatic machines” of not very young “Frenchmen”, when, due to an increase in the temperature of the liquid (especially in traffic jams in summer), they refused to work at all!
Go ahead. It is very important that the dependence of viscosity on temperature be as flat as possible. One of the main criteria for this flatness is the viscosity index: the higher it is, the better. The leaders here are Mobil Multi-Vehicle ATF, Motul Multi ATF and Formula Shell Multi-Vehicle ATF. The “cartoon” of the NGN brand is not far behind them.
Let's see how the viscosity of the liquid in the working area of the box changes, taking into account its heating. The difference is palpable! For kinematic viscosity, it reaches 26%. And the efficiency of "automatic machines" (especially old designs) is quite small and is largely determined by the efficiency of the torque converter - which just suffers when the viscosity of the working fluid decreases.
The smallest drop in viscosity was found in Motul Multi ATF, Formula Shell Multi-Vehicle and NGN Universal ATF oils. The largest is in Totachi Multi-Vehicle ATF. These are, of course, comparative results; a direct transfer to the efficiency of the box cannot be done. But for forced motors, in which the load on the automatic transmission components is higher, it is preferable to have fluids with a more stable characteristic.
Low-temperature properties were evaluated by a combination of several parameters. Obviously, all liquids, including ATF, thicken in the cold. This means that with a fair minus overboard, excessive viscosity will interfere with cranking the engine at the start, since the clutch pedal is not provided on machines with an automatic machine. Therefore, we determined the kinematic viscosity of each sample at three fixed negative temperatures. In addition, we estimated the temperature at which the kinematic viscosity of the oil reaches a certain fixed value, conditionally taken as the limit, at which the gearbox can still be "turned".
At the same time, the freezing point was determined: this parameter is included in all descriptions of ATF and indirectly indicates on the basis of which base the liquid is made - synthetic or semi-synthetic.
Synthetics with a high viscosity index again won in this nomination: Motul Multi ATF, Mobil Multi-Vehicle ATF, NGN Universal ATF, Formula Shell Multi-Vehicle. They also have the lowest pour points. And finally, the protective functions of fluids, that is, their ability to prevent wear. We studied the wear of two models - gearing and plain bearing, since in a real box the operating conditions of these units differ markedly. Consequently, the properties of ATF, which reduce wear, must be different and linked to the operation of the torque converter. And here we found a scatter in the results. The leader in minimizing gear wear is Mobil Multi-Vehicle ATF, while Motul Multi ATF and Totachi Multi-Vehicle ATF won the plain bearing competition by a wide margin.
TOTAL
If during traditional examinations of gasoline and motor oils, as a rule, we revealed only minor differences between one sample and another, here the situation is different. In terms of key parameters, different ATFs have a significant run-up. And given that the degree of influence of this difficult liquid on power, fuel consumption, and the resource of the box is very noticeable, then you should think about its choice. Good synthetics with a high viscosity index are the best choice, which will protect your nerves during a winter start in a fair frost, and will not create problems after a long standing in a traffic jam under the hot sun.
Let's leave the degree of compliance of Multi with its name on the conscience of their developers. At the very beginning, we noted that it was unrealistic to check in practice each ATF in all the "machines" listed on their labels. By the way, in the descriptions (with a few exceptions), tolerances are either directly or by default indicated by the word meets, that is, “corresponds”. This means that the properties of the liquid are guaranteed by its manufacturer, but there is no confirmation of compliance by the manufacturer of the car or box. In conclusion, we would like to inform you that if the planned life of a new car does not exceed 50–70 thousand kilometers (then a replacement is planned), then you read the article in vain - you will not have to change the “liquid clutch”. And in other cases, the information we obtained should come in handy. Adding up the results from all tests, we found that Motul and Mobil were the best products, with Formula Shell slightly behind.
Our comments to each preparation are in the captions to the photographs.
WHAT SHOULD THE ATF BE?
There is no more complex and controversial device in the transmission of a car than an automatic transmission. It combines two units - a torque converter, which ensures the continuity of the energy flow from the engine to the wheels, and a planetary gear change mechanism.
The torque converter is, in fact, two coaxial wheels: pumping and turbine. There is no direct contact between them: the connection is carried out by a fluid flow. The efficiency of this device will depend on the mass of parameters - the design of the wheels, the gaps between them, leaks ... And, of course, on the properties of the fluid located between the wheels. It acts as a kind of liquid clutch.
What should be its viscosity? Too much will increase friction losses in the box - a fair share of power will be eaten, fuel consumption will increase. In addition, the car will become noticeably dull in the cold. Too low viscosity will drastically reduce the efficiency of energy transfer in the torque converter, increase leakage, which will also reduce the efficiency of the unit. In addition, the viscosity of the liquid in the cold increases greatly, and decreases with increasing temperature - the difference can be two orders of magnitude! And the liquid can foam and contribute to corrosion of the box parts. It is desirable that the liquid retains its properties for a long time: then you can not look into the box for years.
That's not all. The same fluid must work in the torque converter, and in the planetary mechanism, and in the bearings of the box, although the tasks and working conditions in these mechanisms differ sharply. In gearing, it is necessary to prevent scuffing and wear, effectively lubricate the bearings and at the same time not interfere with their work with their excessive viscosity: after all, with an increase in viscosity, friction losses increase. But the efficiency of the torque converter also increases with more viscous liquids.
How many options! Therefore, a complex compromise of properties is required that the ATF fluid must combine.
ATF - LIQUID OR OIL?
The classification refers ATF to gear oils, but its purpose is much wider. After all, lubrication of transmission elements - gears and bearings - is not the only (albeit important) function here. The main thing is that ATF acts as the working fluid of the torque converter. It is she who transfers the power flow from the engine to the transmission, because the properties of this fluid are very important for the efficiency of the automatic transmission.
In the passports for ATF, its viscosity indicators are normalized (at operating temperatures and at negative temperatures), as well as the flash and pour points, and the ability to form foam during operation. After all, it is the viscosity that provides lubrication and, therefore, the performance of gears and bearings, the efficiency of torque transmission from the engine to the transmission.
WHAT ARE THE PROBLEMS?
ATF fluids are very capricious. Not always a modern ATF can fit an old machine of the same brand. The same applies to interchangeability: for example, an “automatic machine” from a “Japanese” in 2006 on a specialized ATF addressed to a modern “German” may become bad ... Such an ateefka will lubricate gears and bearings, but the torque converter may be offended and go on strike. Therefore, each automatic transmission manufacturer is looking for its own solution to the problem. And the more difficult it is to make a universal “cartoon” suitable for everyone.
ATF fluid- This is a special gear oil that has a liquid consistency and has a mineral or synthetic base. It is intended for cars running on "automatic". ATF transmission fluid is responsible for performing many functions, for example:
- uninterrupted operation of the gearbox - its control and management;
- cooling and proper lubrication of parts that are susceptible to friction;
- transmission of torque, which passes through the torque converter from the motor to the box;
- ensuring the operation of friction discs.
Many people equate oil with an automatic transmission mixture, but the properties of ATF differ in many ways. To obtain the correct composition, mineral oils are used, to which special substances are added. If you use foreign fluids for "automatics", then this will surely provoke a breakdown of the gearbox, or its complete failure.
The General Motors automobile concern became the manufacturer of the first oil specification. The new mixture entered the mass market in 1949. This was due to the fact that in 1938 the same company developed the first automatic transmission. Subsequently, the automaker came to grips with improving the specifications of transmission mixtures and established the strictest requirements for the composition. Since there were no competitors in this market, GM became the specification setter for the ATF.
The first varieties of liquid were made on fat, which was produced from the fat of sea whales. Due to the release of a law prohibiting the hunting of these inhabitants of the ocean, the corporation had to develop a synthetic base.
At the moment, competition from specifications from General Motors are other eminent car brands - Chrysler, Hyundai, Mitsubishi Ford and Toyota.
Pay special attention to the packaging of the purchased ATF fluid. Consider the type of oil as well as the specification that suits your gearbox.
Types of ATF gear oils
After we have become familiar with what ATF oil is, we will study all kinds of fluid specifications. The very first of them, as noted above, saw the light in 1949 thanks to the efforts of General Motors. The common name for the mixture is ATF-A, which was used on all vehicles equipped with "automatic". In 1957, the specification was revised and thus the Type A Suffix A was born.
So, there are such main types of ATF:
- Mercon- introduced by Ford in the 80s of the last century. They are as close as possible to other specifications and can be compatible with them. The main differences between the varieties from GM and Ford are that the former pays more attention to smooth shifting, and the latter to speed;
- Dexron- Produced by GM since 1968. Since whale oil was used in the manufacture, production had to be suspended. The reason for this was also weak technical characteristics, because the oil showed poor tolerance to high temperatures. In 1972, Dexron ІІС appeared, where jojoba oil served as the basis, which subsequently provoked corrosion of some parts. The next oil, which was equipped with additives that suppress the development of rust, acquired the prefix IID. Fluid with the IIE index was produced until 1993. Its distinguishing feature is the presence of additives that reduce hygroscopic excess. The output of the Dexron III type (1993) became innovative. The novelty retained its liquid properties even at very low temperatures, and frictional characteristics also improved. In 2005, a new generation appeared with the prefix "VI". An ATF transmission oil was developed for use on the new one, which was a 6-band. The mixture has a longer service life, as well as a reduced degree of kinematic viscosity. The last parameter allows you to increase fuel efficiency;
- Alison C-4- developed by General Motors specifically for pouring into large vehicles - off-road vehicles and trucks.
When to change the transmission mixture?
ATF fluid needs to be changed periodically, because this will increase the service life of not only the transmission, but also the car as a whole. Therefore, it is necessary to carry out systematic measurements of the oil level. The replacement period is affected by:
- vehicle mileage;
- terms of Use;
- driving style.
The procedure should be entrusted to specialists at the service station, where there is all the necessary equipment that will allow you to change the oil. After all, you can only drain part of the ATF fluid on your own, a significant part remains in the box. With the help of technical devices, professionals will also be able to wash or replace the filter.
Checking transmission oil in automatic transmission
The long service life of the transmission is ensured by the timely check of the balance of the mixture in the automatic transmission. This operation is carried out in different ways - it all depends on the type of transmission. Before proceeding with the procedure, carefully read the user manual.
You can check the remaining mixture level both on a hot and cold transmission, because the dipstick has the corresponding marks.
If you decide to carry out this operation yourself, then you should remember the need to observe the exact oil level. In each case, you expose the entire system to danger:
- an insufficient level provokes air to enter the pump along with the oil (in this situation, burning occurs, friction slips and a general failure of the system). If you find that the level does not reach the desired mark, then try to determine the cause of the oil leak;
- an increased level causes excess oil to overflow through the breather, the level decreases, therefore, the same problems arise as in the above situation. Emission through the breather is diagnosed by the degree of contamination of the part with liquid.
How to choose a working fluid according to the ATF specification
Each of the groups of oils has different friction characteristics and differences in temperatures. What do the different ATF specifications mean:
- Dexron II does not tolerate too cold temperatures, therefore, it is suitable for use only in those countries where the temperature does not fall below -15 degrees during the winter season. Suitable for cars of previous generations;
- Dexron II it performs well even at temperatures as low as -30, it is necessary only in those areas where severe and frequent frosts prevail. The manufacturer guarantees that the liquid will retain its viscosity. Even if your transmission uses IID, change it to IIE in cold weather;
- Dexron III It is used literally on all modern car models.
An incorrectly selected mixture will provoke multiple malfunctions in the functioning of the automatic transmission. Very predictable slippage of discs, an increase in the time it takes to change gear, the occurrence of jerks at start-up and. All this will be caused by a longer formation of the working oil pressure. Initially, you may not pay attention to such symptoms, but then they will manifest themselves to a greater extent.
Can liquids of different types be mixed?
Mixing liquids is acceptable, but it’s still better not to risk it, because it can lead to breakdown, and a complete replacement of the automatic transmission will hit your pocket pretty hard. In order to identify the type of oil, add a special dye to it, which will not affect the characteristics of ATF oils. If it is not possible to determine the specification, then it is better to completely reload it.
Long-term use of the same fluid, or the use of a low-quality fake, leads to malfunctions and breakdowns in various engine systems.
ATF operation issues
Transmission longevity depends on maintaining optimum fluid levels. If you know what ATF is, then you also know that oil changes are carried out only in car services under the supervision of specialists.
The fact that something is wrong with the liquid is indicated by its black or dark brown color. At the same time, a burning smell is observed. The color of a normally functioning transmission oil is deep red or red with an orange tinge.
As noted above, it is important to prevent fluid transfusion. Foaming of the oil provokes its release through the breather. If the level is insufficient, then the pump captures air. This affects the clutches - the discs begin to slip and burn out.
