The gears do not run on traditional gear oils. They are filled with special ATF oil. This fluid is a high-index mineral or synthetic based formulation. Such fluids for automatic transmissions allow the operation of systems that control and manage gear changes. Also, through this fluid, torque is transmitted from the engine to the automatic transmission. Additionally, ATF oil lubricates the friction parts and cools them.
How ATF fluids were created
The first automatic transmission was created in 1938. This design is called Hydramatic. It featured a vacuum gearshift system. This unit was created by Pontiac engineers. Even then, the company was part of the General Motors auto concern.
Since before the launch of any innovative development, they preferred to pre-check it and test it in every possible way, the new automatic transmission was installed on Oldsmobile. The tests went well. And now, in 1939, the Hydromatic was installed as an option on the Oldsmobile Custom 8 Cruiser car. This option cost $57.
The role of General Motors in the creation of the first ATF
By the end of the 40s, automatic transmission had become a familiar part of cars. And it is not surprising that the first ATF oil for automatic transmissions was created by General Motors specialists. It was the world's very first specification for a transmission fluid. It was called Type A. The liquid was created in 1949. Then GM began to develop gear oils, and later classify, put forward the most stringent requirements for them. Products that were created in the laboratories of General Motots, due to the lack of competition, have become the international standard for working fluids for any type of automatic transmission.
From to new technologies
In 1957, the already successfully existing specification was revised and decided to add one small new application - Type A Suffix A transmission fluid (abbreviated name ATF-TASA). After 10 years, they created specification B (this is ATF Dexron-B).
As the main ingredient, due to which the liquid had lubricating properties, blubber was used - this is fat that was obtained from whales. But then the development of technology in the production of automatic transmissions forced the concern to introduce something new. So, in 1973, a new Dexron 2C specification is being developed. In 1981, it will be replaced by Dexron-2D. After a flurry of negativity from animal advocates hit the corporation, as well as after a ban on catching whales, the company in 1991 creates the innovative Dexron-2E formula. The difference of this product is that it is created on a synthetic basis. Previously, the lubricant was produced on a mineral basis.
Birth of Dexron-4
In 1994, the entire world community learned about the new specifications, which set out new requirements for viscosity properties and temperature characteristics. Also, the specification implied more improved frictional properties. These are Dextron-3F and Dextron-3G. After 8 years, Dextron-3H comes out. But the most modern and most rigid is ATF Dexron-4. Of course, today there are other specifications from other car manufacturers. These are such giants as Ford, Toyota, Huinday and others.
How is ATF different from other gear oils?
To understand the difference, you need to approach the issue from afar. In cars, oils are used for the engine, gearboxes, hydraulic boosters and ATF oil. What are the similarities between all these liquids? These oils are based on hydrocarbons, which are obtained through the processing of fossils. This gives some similarities in characteristics. All of these agents have lubricating properties, increase slip between rubbing surfaces.
Also, all these fluids have good heat dissipation characteristics. They are similar in texture. This is where all the similarities end. This is sometimes the cause of gross errors when a novice motorist pours oil for “mechanics” into the automatic transmission, and brake fluid into the power steering.
Main properties of ATF
ATF oil is one of the most complex fluids in its composition among all lubricating mixtures used in a modern car. Such lubricants are subject to high requirements and standards. The oil should have a lubricating effect - due to this, friction is reduced, and at the same time, wear in the gearbox elements is reduced. In this case, the friction forces in the friction groups should increase. This will reduce slippage of other nodes.
Also one of the important properties is heat dissipation. The oil has high thermal conductivity and fluidity characteristics. In this case, the liquid should not foam during operation. An important point is stability, namely the absence of oxidative processes when heated to high temperatures at the time of contact with oxygen. Additionally, the oil must also have anti-corrosion properties. This is necessary in order to prevent the formation of corrosion on the internal components of the mechanism. Automatic transmission fluid must be hydrophobic (this is the ability to expel moisture from the surface). In this case, it is necessary that the liquid retains its flow characteristics and hydraulic characteristics. ATF grease has stable characteristics and a high compression ratio over the widest possible temperature range. Another point is a decrease in penetrating ability through automatic transmission and the presence of a dye.
Typical characteristics for automatic transmission lubricants
Consider several ATF oil specifications, characteristics and numbers. For the Dexron-2 specification, the kinematic viscosity is 37.7 at 40 C. At 100 degrees, the same parameter will be 8.1. For Dexron-3, kinematic viscosity is not standardized at all, as well as for other specifications.
The viscosity of ATF oil according to Brooksfield for Dexron-2 at a temperature of 20 degrees should be 2000 mPa, at 30 - 6000 mPa, at 40 - 50,000 mPa. The same parameter for Dexron-3 will be 10 if the pressure is 1500 MPa. Flash point - no lower than 190 degrees for Dexron-2. For Dexron-3 - this parameter is 179 degrees, but not higher than 185.
ATF oil compatibility
Any oil (whether mineral or synthetic) can be mixed without any consequences. Naturally, more modern fluids have improved characteristics and properties. If a modern liquid is added to an ordinary one, this will improve the properties of the filled oil. The older the specification, the lower performance it will have. Also, the shelf life of ATF oil is an order of magnitude lower. Experts recommend changing this fluid every 70 thousand kilometers. It is worth noting that many modern manufacturers do not regulate the replacement period for this fluid. It is filled for the entire service life. But when a car takes care of 200 thousand kilometers on one oil, this is not very good. The fact is that the fluid in the automatic transmission is working. It is she who transmits torque from the engine to the wheels. This oil is constantly in action, even when the car is in neutral speed. Over time, it collects the products of development.
These are metal shavings that clog the filter and sensors. As a result, the box ceases to function normally. Now to the issue of compatibility. No brand will ever fully disclose all information regarding the composition and properties of the fluid produced. Often, manufacturers are limited to only marketing information and advertising that forces you to buy only a specific product. But often this information is not substantiated. For transmissions with hard engagement of torque converter lockups, it is recommended to use fluids with constant frictional characteristics.
For automatic transmissions with GTF blocking, products with variable properties should be poured. And finally, regardless of the automatic transmission model, all parts, bearings, gears and other elements are made from the same materials. This means that different types of ATF are not particularly different from each other.
About application features and compatibility
If the oil in the box changes entirely, then it is best to purchase a more expensive product. In this case, constant or variable frictional characteristics must be taken into account. If the budget is limited, then even ATF universal oil will do. Its use will not affect the quality of the box. If the liquid is added, then experts recommend using products of a class higher or at least not lower than the filled one. But if its resource has reached 70 thousand kilometers, a complete replacement is necessary. Additional flushing is recommended. This operation takes an additional 20 liters of oil. It is not cheap, but judging by the reviews, this operation perfectly washes the chips. And its presence, as you know, complicates the operation of an automatic transmission.
So, we found out what ATF oil is for automatic transmission.
Automatic transmission requires a special transmission oil - ATF. It consists of a synthetic base together with a mineral one. As a result, ATF ensures the normal operation of the system in the automatic transmission that controls gear shifting. In addition, with its help, torque is transmitted from the motor to the gearbox. ATF also cools parts and reduces friction.
ATF oil properties, benefits
ATF is very different from similar products. Its color has a pronounced red color. Only proven high-quality components are used for manufacturing. Production is carried out in America.
The high quality of gear oil is confirmed by international standards. It belongs to the group of all-weather and can be used all year round.
- It starts to freeze when the temperature drops to -40.
- Has high fluidity.
- Prevents corrosion.
- It has excellent antioxidant properties.
- Does not form foam.
The automatic transmission on such a TM works almost silently, ensuring a smooth ride of the car. Manufacturers recommend pouring ATP into mechanical gearboxes as well.
Automatic Transmission Fluid Compatibility
In principle, theoretically any oil can be mixed. Moreover, since modern compositions are distinguished by improved characteristics, when mixed with “normal”, its initial properties will improve.
Professionals recommend a complete oil change after 70,000 runs. I must say that most modern manufacturers do not determine a specific replacement period. Car oil is filled for the entire period of operation of the car.
However, if the vehicle runs on the same lubricant for more than 200,000 kilometers, this can lead to negative consequences.
The reason is simple. The fluid in the automatic transmission performs an important function. It transmits the engine torque to the wheels. In other words, the oil is at work all the time, even if the machine is not moving. Time passes, metal shavings fall into it. It begins to clog the filter, interferes with the full operation of the sensors, and all this as a whole leads to a breakdown of the box.
When it comes to oil compatibility, you must always remember that the leading manufacturers of transmission fluids never fully disclose their composition.
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 fluids.
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.
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 under pressure are swirling. 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.
ATF replacement in ZF automatic transmission
|
Despite all its well-known brands (Sachs, Boge, Lemfoerder), ZF is primarily associated in specialist circles with automatic transmissions. In addition to high-tech and high-quality products, the company provides its partners with all the necessary tools and knowledge for the diagnosis, maintenance and repair of automatic transmissions. The next step on this path was the removal of training seminars outside of Germany. The first such seminar in Ukraine took place in September 2015 and was dedicated to the replacement of ATF in automatic transmissions manufactured by ZF. |
ATF replacement in ZF automatic transmission
Why and how often do you need to change the ATF? How to perform this procedure correctly? autoExpert got acquainted with the opinion of ZF Services specialists on these issues at seminars held in Germany and Ukraine.
Despite all its well-known brands (Sachs, Boge, Lemfoerder), ZF is primarily associated in specialist circles with automatic transmissions. In addition to high-tech and high-quality products, the company provides its partners with all the necessary tools and knowledge for the diagnosis, maintenance and repair of automatic transmissions. The next step on this path was the removal of training seminars outside of Germany. The first such seminar in Ukraine took place in September 2015 and was dedicated to the replacement of ATF in automatic transmissions manufactured by ZF.
ATF is often referred to as "oil", but this is incorrect. After all, automatic transmission fluid, even in literal translation, is a fluid for automatic transmissions. It not only lubricates the mechanisms, but also participates in controlling the operation of the box. For a long time it was believed that ATF in automatic transmissions is designed for the entire life of the part and cannot be replaced. But recently, the automotive industry has begun to abandon this doctrine. ZF Services recommends changing the ATF in automatic transmissions manufactured by them every 80-140 thousand kilometers, but at least once every 8 years. Today, these recommendations are joined by BMW, Mercedes and other European automakers.
How automatic transmission works
Automatic transmission is a very complex unit. It has a set of planetary gears that are used to transmit torque from the engine to the wheels. And in order to set the direction of rotation of the shaft at the outlet of the box or change the gear ratio, it is necessary to block or connect certain gears. The role of the "switches" is performed by special brakes and clutches (frictions), driven by an electronically controlled hydraulic system.
To change gear, a modern "automatic" needs from 400 to 200 ms, and in boxes installed on sports cars, this figure is reduced to 80 ms. Electronics opens the desired valve through which ATF enters under high pressure, closing the desired clutch or brake.
A group of participants in a seminar on changing fluid in automatic transmissions. Schweinfurt, Germany.
Why change the ATF?
Initially, a 5-6-speed automatic transmission contains about 10 liters of ATF. But over time, the process fluid is produced, and upon reaching 100-120 thousand kilometers, the losses usually amount to 1-1.5 liters. This is 10-15% of the ATF volume in the automatic transmission.
With such losses, the load on the hydraulic shift control system is greatly increased, and its efficiency is reduced. The liquid in the sump shifts on slopes and turns, and if the level is insufficient, the pump may entrain air. This will create pressure problems in the shift control system.
A high concentration of ATF-contaminating waste products can harm the automatic transmission oil pump.
The maximum allowable period for using ATF is the period during which the fluid is guaranteed to retain its qualities and ensure the quality of the gearbox. Changes in ATF occur not only with increasing vehicle mileage, but also over time. If the car has stood for many years without movement, and then they began to actively drive it, then for the first months the driver will not feel any malfunctions in the operation of the box. However, the wear curve of an automatic transmission when driving with over-aged ATF will be much steeper than the wear curve of a box in which the transmission fluid was changed regularly and in a timely manner. ZF recommends changing the ATF at least once every 8 years. This is the maximum period of absolutely safe use of the liquid with minor loads on the box and mileage on it, far from the maximum allowable standards for one fill - 80-140 thousand km, depending on the model of the box.
A new fluid always has the best lubricating properties. Thanks to them, the operation of automatic transmission mechanisms improves. Shift control valves begin to operate faster and smoother. Reduced fuel consumption and increased overall driving comfort. And this is only the obvious part of the advantages of replacing ATF. Not obvious are the control of the state of the automatic transmission (based on the analysis of the fluid drained from the box) and the extension of the service life of the unit.
An example of a sticker warning that ATF replacement is not necessary.
Preparation for ATF replacement
Before proceeding with the replacement of ATF in an automatic transmission, it is necessary to make sure that the engine is idling properly. This is done using suitable diagnostic equipment and is necessary to adjust the transmission fluid level.
If the idle speed is OK and there is no need to adjust it, it is necessary to make a test drive. This allows you to check the operation of the automatic transmission and the quality of gear shifting, as well as bring the temperature of the ATF to operating values.
After completing the test drive, the car is put on a lift, having previously switched the box to the “P” mode.
When you first look at the automatic transmission oil pan of a car on a lift, there is a chance you will see a yellow sticker notifying that the process fluid filled in is designed for the entire life of the car and does not need to be changed. Until 2014, all cars were supplied with such stickers, and some automakers continue to do so today. The catch is that this so-called “lifetime” of the car’s operation, according to the manufacturers’ plan, is limited to 140-180 thousand kilometers. But most cars travel much longer distances, living 2-3 or more "lives". This increases the demand for maintenance of various units and assemblies and, in order to avoid loss of image, forces manufacturers, primarily units, to issue appropriate instructions for the correct and timely maintenance of their products.
|
A plate engraved with the serial number of the part is located on the gearbox housing. On the case of the automatic transmission there is a plate indicating the type, model, serial and catalog numbers of the box. At the ZF seminars, the demonstration was carried out on a ZF 6HP21 automatic transmission with a mileage of 80 thousand km. This information allows you to determine the ZF ATF replacement kit number, process fluid grade, and replacement procedure. In total, for 5- and 6-speed ZF automatic transmissions, there are three options for this procedure, the differences in which are the gear shift sequence when the box is filled with new fluid. ATF selection ZF Services strongly recommends using genuine ZF process fluids or those supplied by the vehicle manufacturer when replacing ATF. You can suspect the company of looking for its own benefit, because ZF does not produce ATF on its own. But everything is not so clear. For automatic transmissions that ZF plans to put into production in 2018, ATF has been tested by the company's specialists since 2011. That is, at the time the gearbox enters the market, the ATF testing period will reach 7 years. It is also important that transmission fluid companies do not have the right to reproduce ZF's ATF formula in other own branded products. In other words, ZF automatic transmissions are designed for certain ATFs that are only available in ZF branded packaging or bottled in the manufacturer's original packaging. ATF replacement kits The complete set of kits for changing transmission fluid in ZF automatic transmissions is different and depends on the model of the box. They can be divided into two categories: for boxes with a metal and for boxes with a plastic pallet. Metal sump box kits contain a set of sump gaskets, drain and filler plugs in the sump, a replacement oil filter, a set of magnets to remove metal particles from the ATF. The kits for boxes with a plastic tray include a replacement tray assembly (with filter, magnets, plugs and gaskets) and a set of bolts for its fastening. Also, all kits contain 7 liters of ATF in a 1 liter package and printed instructions for changing transmission fluid in ZF boxes. 7 liters is the volume required to partially replace the ATF. For a complete replacement, you need to buy another 3-4 liters.
|
ZF ATF replacement kits for boxes with metal (left) and plastic (right) pallets.
The cost of a ZF transmission fluid change kit is approximately equal to the combined cost of all of its parts. But it is much more convenient to get everything you need in one box.
Drain ATF
Before unscrewing the drain plug in the automatic transmission oil pan, it is necessary to prepare a container of a suitable volume and take measures against possible pollution of the environment by transmission fluid splashes. The amount of ATF that will spill out of the drain hole of the box may be different and depends on the degree of fluid production. You should count on 5-6 liters. The drain hole is not at the lowest point of the sump, the bottom part is occupied by the filter and some oil remains in it. To remove it, you need to remove the pan.
Before continuing the ATF replacement procedure, you need to make sure that everything is in order with the box. To do this, you need to check the quality of the drained fluid. It should not smell burnt, it should not contain small paper particles from the friction rings of the transmission. In this case, the color of the drained liquid may differ significantly from the color of the new one - this is normal for ATF, which changes its properties due to repeated heating.
The presence of heavy deposits or large metal particles on the magnet in the pan indicates a malfunction of the box. In this case, the oil change should be stopped, and the faulty spare part should be sent for repair. In a working automatic transmission, the magnets should be clean. A slight matte coating is allowed.
On the inside of the pallet, you need to inspect the magnets. A matte coating is acceptable, but the presence of large metal particles indicates serious problems inside the box. In the presence of the above problems, the oil change should be stopped, because the gearbox needs to be repaired.
Partial or full replacement?
In theory, when the master drained the ATF from the automatic transmission, removed the pan and made sure that there were no signs of malfunctions in the box, you can start replacing the filter (in the case of a metal pan), installing the pan and filling the ATF. At this moment, 5-6 liters of fluid out of 10 have been drained from the gearbox. But you can “drive” another 2-3 liters out of the box. To do this, you need to remove the mechatronics - the electronic control device for the automatic transmission.
It is difficult to remove the protective sleeve of the mechatronics with your hands, so the master resorts to using a mount. This operation is absolutely safe if the tool is in capable hands.
There is an opinion that the removal and installation of mechatronics back can lead to automatic transmission malfunctions. In fact, everything is not so. In Europe, ZF annually conducts about 40 trainings on ATF replacement in automatic transmissions. Each time the trainer arrives at the seminar site in a demo vehicle, removes and installs this unit when changing the ATF, and then drives back. This does not cause any problems. The main thing is to do everything right.
To remove the mechatronics, you need to disconnect the connector of the contact group of wires from it, then pull out the latch that fixes the protective sleeve and remove the sleeve itself. This is not easy to do - the available space is too small to comfortably grab it, so the ZF trainer at the seminar resorts to using a mount. In most cases, the bushing breaks when removed and should be considered a consumable.
 |
There are two more arguments in favor of replacing the removed protective sleeve with a new one. Firstly, when reusing an old bushing, there is a risk that the seals on its surface do not fit snugly enough to the mechatronic housing. This can lead to ATF leakage and water ingress into the box. Secondly, there may be red oil seals on the sleeve. This means that this sleeve is an old model. ZF now produces bushings with black oil seals - more durable and reliable. In any case, the cost of a new bushing is negligible, and there is no reason to save on its replacement. However, this part is not included in the ZF ATF replacement kit and must be purchased separately. When disconnecting the wires from the mechatronics and removing the protective sleeve, you need to remember that the discharge of static electricity from the hands of the master can damage the electronics of the assembly. Appropriate measures should be taken: use grounding bracelets and shoes, carry out work in special protective gloves and avoid touching the mechatronics contact group with your fingers. |
After disconnecting the wires and removing the protective sleeve, you can proceed to remove the assembly. The number of bolts holding the mechatronics may be different. ZF produces 760 modifications of this device. You need to unscrew the bolts with large heads (M40), they attach the mechatronic to the automatic transmission. Bolts with small (M27) heads hold the assembly elements together. They can not be unscrewed, otherwise it will simply fall apart. First you need to unscrew the bolts on the plastic part of the device in order to avoid excessive stress on the plastic, then proceed to unscrew the necessary bolts on the metal part. When removing the unit from the box, ATF will flow, so you should substitute a container in advance to collect it.
Removing the mechatronics opens up access to the holes through which ATF enters the device from the automatic transmission and vice versa. By supplying compressed air into one of the holes, it is possible to expel the remaining liquid from the torque converter. After that, you can begin to install the mechatronics and the pallet in place.
|
You need to unscrew the bolts with large heads (M40), they attach the mechatronic to the automatic transmission. Smaller bolts (M27) fasten the parts of the device together. |
Removing the mechatronics opens up access to the holes through which ATF enters the device from the automatic transmission and vice versa. |
Torque converter air purge. |
When installing mechatronics, you first need to screw in the bolts that fix its metal part to the box, then screw the bolts that fix the plastic part. There is no specific torque for tightening these bolts, it is enough to feel that the bolt is tightened. The box bodies and mechatronics are either made of aluminum or magnesium alloy, so excessive zeal with tightening the bolts is inappropriate here. In this case, there is also no order for tightening the bolts in a circle; common sense should be followed.
 |
 |
After prolonged use, the sealing gum on the "glasses" is jammed. For this reason, reusing the part may compromise the tightness of the connection of the ATF circulation holes between the mechatronics and the automatic transmission. The part is to be replaced.
When installing the device back on the car, it is necessary to replace the so-called "glasses" - a plastic part with an oil seal that provides a tight connection of the holes for ATF circulation between the mechatronics and the automatic transmission. This part costs only a couple of euros. If you compare the removed "glasses" with the new ones, you can see that the gaskets of the old part are crumpled. This means that there is a risk of an insufficiently tight connection.
What you need to know about pallets
In the case of a metal automatic transmission oil pan, everything is simple and clear. It is necessary to replace the oil filter, magnets, a gasket that ensures the tightness of the connection with the box, and install the pan, guided by the bolt tightening scheme and tightening them to the appropriate torque (for steel pans it is 12 Nm, for aluminum pans - 4 Nm + 450).
The plastic pallet is quite expensive, but you can’t save on replacing it. And it's not just the ATF filter, which is part of the sump. The fact is that it is impossible to ensure complete tightness of the connection of the re-installed plastic pallet with the box.
Because all ATF replacement training in Germany is done on the same vehicle, ZF Services experimented with reusing plastic pallets to reduce costs. However, it turned out that the tightness of the connection of the pallet with the box is not fully preserved. ATF, of course, did not spill onto the road, but traces of leakage were clearly visible on the pallet. It was not possible to re-ensure tightness even with the use of special adhesives and sealants, and it is impossible to replace the gasket with a new one, because it is fixed around the perimeter of the pallet at the factory. Therefore, the company abandoned this idea.
 |
Why doesn't ZF just make all transmission pans metal? Everything is very simple. Automakers are trying to keep the cost of producing cars as low as possible, and plastic pallets are cheaper to manufacture. If the reliability of two parts made of different materials is the same, then the car manufacturer will choose the cheaper one. ZF is an OEM supplier, so the opinion of the automaker is decisive in this matter. Thus, both automakers and ZF earn on pallets. When installing the pallet on an automatic transmission, you must follow the bolt tightening scheme, which is the same for both plastic and metal pallets. This helps to avoid distortion. Tighten the fixing bolts of the plastic pallet with a force of 10 Nm. ATF filling in automatic transmission Before you start pouring ATF into the box, you need to do the following: make sure that the pump contains a sufficient amount of liquid (at least 7 liters for partial and at least 10 liters for complete ATF replacement), check that the plug is screwed into the drain hole correctly and tightened whether it is with the right moment. The tightening torque can be obtained from the documentation supplied by ZF with each ATF replacement kit. You should also connect the car to a diagnostic device that can read information about the box (KTS, Launch, "VASYA diagnostician" and the like). |
Further actions in an ideal situation will require the participation of 3 people. One will fill the ATF in the automatic transmission, the second will turn on the car engine at the right time so that the oil pump starts pumping fluid from the sump into the gearbox, and the third will provide communication between the first two. The role of the third participant in the process may seem insignificant, they say, can two experienced craftsmen really not be able to find a common language in such a simple procedure? But in fact, it is quite difficult to make out the words of a colleague coming from under the car with the engine running, sitting in the cabin even with the windows down.
A real case from the practice of ZF trainers. While pouring ATF into the sump, a lack of fluid in the pump was revealed. The most experienced coach announced the problem to an equally experienced assistant, who was in the cabin of the demonstration car. Instead of a request to bring more ATF, the assistant heard the command to turn off the engine. The result of his actions were several liters of consequences flowing, in the literal sense of the word, from the box of the car directly onto the coach under it.
The first stage is filling the automatic transmission pan. The ATF filling hole can be located in the side or bottom of the sump, depending on its modification. The location of the filler hole only affects the choice of the tip for the oil supply hose - a curved "goose" in the case of the lower location and a regular flexible hose of the right diameter for the hole located on the side.
ATF is poured into the sump until liquid begins to flow out of the filler hole. Then you should turn on the engine (second person) and continue to pump fluid intensively. When the engine is running, the automatic transmission oil pump pumps fluid into the torque converter. Filling continues until the liquid again begins to flow out of the filler hole in the sump. Now you can screw the hole with a plug and only after that turn off the car engine.
ATF is poured in until it starts to flow out of the filling hole.
Setting the correct ATF level in automatic transmission
Before checking the correctness of the ATF level, it is necessary to “drive” the fluid through the gearbox by turning on the engine again. For the ZF automatic transmission, there are three schemes for performing this operation, which are used depending on the modification of the box.
The first scheme provides for sequential automatic transmission switching to modes R, D and gear shifting from 1 to 3. It is necessary to linger in each gear for 3 seconds. In winter, gear shifting is carried out in manual mode.
The second scheme is similar to the first, but you need to shift gears up to 4.
The third scheme provides for the inclusion of modes R, D and all gears with a ten-second delay on each. Then you need to fix the engine speed at around 2000 to fill the torque converter. After completing all the steps according to the desired scheme, you should switch the automatic transmission to the “P” mode.
If the machine is installed on a lift, then all the necessary operations can be performed directly in the box. In the case when the ATF is replaced in the inspection hole, you will need to perform a test drive to run the fluid through the box - shifting gears above the second and leaving the car stationary will not work.
After completing the above transmission manipulations, check the ATF temperature by looking at the scan tool screen. Correct determination of the amount of filled liquid is possible at its temperature of 30-350C. If the temperature is lower, the gearbox must be allowed to warm up. If higher, let cool. If the ATF temperature is within the prescribed values, the fluid filler hole in the transmission sump must be opened. ATF should flow from the filler hole drip. If the liquid does not pour out, topping up is necessary.
Having brought the ATF operating temperature to 400C (a small error is permissible, but the temperature should not exceed 500C) and making sure that the liquid is poured out as expected, it is necessary to tighten the filler plug with the prescribed tightening torque and then turn off the car engine. Work on replacing ATF in automatic transmissions has been completed.
Where to find the necessary information
The tightening torques of the automatic transmission oil pan bolts, drain and filler plugs, the type of program for pumping ATF into the torque converter and gearbox, as well as other useful information can be found in sources such as TecDoc, InCat, WebCat or in the printed service information of ZF Parts. Also included with each ZF ATF replacement kit in the gearbox is a manual for this procedure.
Do I need to reset the adaptation data?
ZF automatic transmissions are adaptive, like most modern automatic transmissions. They are able to "adjust" to the individual driving style, providing smooth and timely gear changes. This learning happens automatically. It is enough for the driver of a new car to drive 500-1000 kilometers in order for the box electronics to recognize his driving style and start shifting gears in an ideal mode for him.
Modern diagnostic tools allow you to reset this data to factory settings. This procedure is necessary if the automatic transmission has been repaired (for example, the friction discs have been changed in it). Sometimes it is used for a radical change in driving style (from aggressive-sporty to calm or vice versa), when the new owner of the car feels discomfort from the operation of the box.
ZF Services service engineers do not recommend doing an adaptation data reset after a normal ATF change in an automatic transmission. This will cause more problems than good. First of all, you will have to explain to the car owner why, after servicing his car, the gears began to switch hard and why he, who paid money for the ATF replacement, will have to endure this for the next few hundred kilometers.
Editorial
The information presented in the article describes the process of replacing ATF in 5- and 6-speed automatic transmissions manufactured by ZF, equipped with an oil pan. autoExpert has no information on whether the described methods are applicable when changing the process fluid in automatic transmissions from other manufacturers.
