The quality of motor oils determines the normal and long-term functioning of automobile engines. This raises the question, which engine oil is the most effective? In the modern market, buyers are provided with a huge selection of lubricants, and it is not possible for anyone to conduct appropriate tests for each variety. For this reason, several basic stages have been developed for determining the quality of all varieties of motor oils.
Such tests primarily refer to synthetic lubricants of the seven most popular brands that are poured into the engines of modern cars. The viscosity of these fluids corresponds to the 5W-40 mark, and in terms of performance they are included in the SJ / CF group according to the API classification.
What exactly is being checked?
There are many different criteria for comparing the performance of semi-synthetic and synthetic motor oils. Motor tests are considered as objective and complete as possible, but at the same time, such verification methods are also the most expensive, so they are not used in our country. Scientists have to be content with the simplest chemical methods for testing motor oils.
Determination of the sulfate ash content of the oil allows you to set the amount of carbon deposits in the combustion chamber. Oil enters there through the piston rings and flows down the walls of the cylinders. The quality of the functioning of the ignition system, as well as the “cold” start, directly depends on the amount of ash.
Car owners are most interested in protecting vehicle components from wear. Appropriate performance characteristics provide an optimal level of oil viscosity when operating in certain temperature conditions. It is also obligatory to carry out a friction test using a special four-ball device.
The viscosity index is determined before and after the thermal oxidation procedure. Such a procedure involves the artificial aging of lubricants, which can be achieved within 20 hours with continuous high temperature exposure, corresponding to 200 degrees and the simultaneous passage of an air mass through the liquid using a copper catalyst.
The duration of the process of neutralizing acids formed during engine operation, which contribute to the formation of corrosion and accelerated wear of parts, is also considered important. Determining the base number of engine oil makes it possible to determine the duration of its protective properties.
Synthetics and semi-synthetics
Before testing domestic oils, it is recommended to pay attention to the model of the machine with which the test is being carried out, as well as to its technical condition. Everyone needs to know the main distinguishing characteristic of lubricants. Synthetics is a synthesized liquid obtained after deep processing of raw materials. In the process of developing such oils, the synthesis of molecules is considered to be the main one. Such materials are distinguished by the maximum indicator of stability when interacting with the environment. Synthetics do not lose their performance characteristics for a very long time.
Semi-synthetics is a product that is created by combining several different bases. The proportions in the manufacture of such oils for synthetics are 30-50%, and for mineral-based fluids - 50-70%. The mineral base is obtained through oil refining.
To choose the right lubricant, it is recommended that you familiarize yourself with their main features:
- Synthetic-based fluid is characterized by increased fluidity and penetrating power. The consumption of such lubricants is significantly reduced. The motor wears out less during operation and does not require additional maintenance so often. Synthetics do not change their properties as a result of overheating and exposure to low temperatures.
- Semi-synthetics are always relevant for gasoline and diesel engines. In addition, such tools can operate cold power units with particular efficiency.
synthetic or semi-synthetic
Sulfated ash content
During the combustion of engine oil, combustion products remain due to the presence of metal-containing additives in the composition of the lubricant. The initial level of ash content of the liquid should be less than 0.005% with a possible increase to 0.4-2% when additional additives are added to the composition. The ash content should not exceed the established norm, since when penetrating into the combustion chamber, deposits may form, causing glow ignition, which ultimately leads to a short circuit of the electrodes in the spark plugs.
In addition, the wear of components increases significantly due to the abrasive effect on some friction areas. Pistons crack and melt, exhaust valves often burn out due to insufficient heat dissipation.
Consider the optimal ash content of lubricants for specific types of vehicles:
- Gasoline engines of vans, minibuses and cars - a maximum of 1.5%;
- Diesel engines - a maximum of 1.8%;
- In diesel engines of road trains or heavy goods vehicles, the permissible maximum corresponds to 2%.
Viscosity
This indicator is determined at various temperature effects. Thus, the optimal temperature range is revealed to ensure the highest quality lubrication of components when starting a cold engine, pumping lubricants with a pump, normal processing and protection and cooling of engine components.
The kinematic viscosity test is considered one of the main evaluation criteria for the viscosity-temperature indicators of domestic and foreign, synthetic and semi-synthetic materials. The viscosity index allows you to characterize the level of change in a given property of a liquid. The higher this indicator, the better the viscosity-temperature characteristics can be considered.
The tests were carried out in accordance with the developed methods in laboratory conditions using high-tech equipment. The results were then compared against clearly defined quality standards.
Base number
As lubricants age, a certain amount of acids are formed, which will later be converted into neutral chemical compounds. If this does not happen, acids contribute to the corrosive wear of the constituent elements of the motor and the formation of carbon deposits. The neutralizing properties of motor oils always decrease during the operation of the car. Lubricants lose their suitability after the base number drops to certain levels.
Excess alkalinity also has a bad effect on the performance of the motor, contributing to increased corrosive wear of components and accelerating the formation of deposits.
Dirt build-up and acidity levels are kept at an acceptable level if the alkalinity of the lubricants is high enough. It should be borne in mind that a liquid with a high alkaline number changes its color very quickly if it is poured into a dirty motor. On the surface of engine components, a substance containing a large amount of alkalis contributes to the accelerated erosion of the deposits formed. This is not a cause for concern, since the darkened substance will not lose its characteristics during the standard period of operation.
Comparison of SAE 5W-30 lubricants
Domestic experts conducted a comparative test of several of the most popular types of lubricants for car engines with a viscosity index corresponding to SAE 5W-30.
For testing, three canisters of each sample were used, the volume of which was 4 liters each. 2 canisters are needed to replace the fluid after running in, and the third was topped up during the tests. In order for the test to show the most accurate results, only the same cars were used, each of which covered approximately 10,000 km during the testing period.
Consider the list of tested lubricants:
- Castrol Magnatec A1;
- G-Energy F Synth EC;
- Mobil Super FE Special;
- Motul 8100 Econergy;
- Shell Helix Ultra Extra;
- THK Magnum Professional C3;
- Total Quartz 9000 Future;
- ZIC XQ LS;
All substances darkened almost simultaneously after passing 2.5 thousand km. The conclusion suggests itself that each liquid washes a car engine well enough. There was perfect cleanliness under every valve cover. At the same time, it was easy to notice the difference in performance at low temperatures. All lubricants, except for Castol, did not create any difficulties in starting the engines. A drop test using a probe also showed optimal results.
The first car to require topping up was the one with Mobil oil in the engine. Its level was reduced to a minimum mark in just some 4.8 thousand km, so it became necessary to add an additional 680 g, and when the mileage was 8000 km, it was necessary to add the same amount. Engine filled with Total fluid. It should be noted that synthetics were consumed much more slowly. This indicates that the mileage between each visit to the service increases significantly.
At the same time, all cars were filled with the same fuel, the quality of which the specialists did not raise any doubts. The test showed that the consumption of gasoline was almost the same. As expected, the least viscous G-energy lubricant was the most economical option, and the viscous Shell was the most wasteful fluid. The difference in consumption was approximately 3%.
It should also be noted that each engine oil has shown itself at a decent level in terms of protecting the car engine from wear. When operating at maximum power, the greatest damage occurred to the piston rings, which were chrome-plated. The chromium content of the lubricants used after the test was carried out was almost zero. The motor was running at a speed of 6000 rpm. for 100 hours. The level of concentration of other metal components in the lubricants was not exceeded during the wear test.
The test showed that THK, Castol, Motul oils are endowed with the most effective oxidizing properties. Upon completion of the tests, the maximum base number coefficients were maintained in these liquids. The last place in this category was taken by the products of G-energy, ZIC, Shell.
Features of lubricants 5W-30 and 5W-40
Lubricants with a viscosity index of 5W-30 are considered to be an all-season innovative product of the best quality. Such products can be used in gasoline and diesel engines. When synthesizing such oils, a special formula is used, which involves a combination of a synthetic base and additives, for the creation of which the most advanced technologies are used today. Thanks to this combination, the friction of the motor components and, accordingly, their wear are significantly reduced.
The resistance of such a lubricant to oxidation significantly increases the duration of the motor. Regardless of the conditions in which the car is operated, its functionality will always remain at the highest possible level.
5W-40 engine oils are mostly synthetic based and can also be used in gasoline and diesel engines. Lubricants can be poured into cars, SUVs and even small trucks. Such fluids are recommended for use in cases where engines experience significant loads.
At low temperatures, this lubricant has excellent fluidity. A drip test using a dipstick always shows the required results. At the same time, the viscosity level is maintained for a long time. The quality of the lubricant will not deteriorate depending on the conditions in which the machine is used. This improves the functioning of the mechanisms of catalytic afterburning of particulate filters, as well as exhaust gases. Thanks to such qualities, car engines can be operated much longer without using the services of car services.
When considering these two types of lubricating fluids, we can say that the 5W-40 option is the most preferable for use in vehicle engines.
The main distinguishing feature of 5W-40 is considered to be a fairly good viscosity index, which is noted in the summer when the liquid is exposed to high temperatures. Thanks to these features, the lubricant contributes to the smooth and constant operation of vehicle engines.
Summing up
The quality of lubricants for car engines is determined in various ways. A large number of products on the market today does not allow the use of one method of verification for each individual variety. Therefore, it can be argued that it is almost impossible to achieve high accuracy of test results for all existing motor oils according to some specific criteria.
The best option for checking the quality of liquids to determine their actual performance is considered to be a test in real conditions, which means that such an event will require a number of cars corresponding to the number of all types and types of existing lubricants. At the same time, the cars must be exactly the same, operated in the same weather conditions and refueled from the same fuel tank.
And a little about the secrets of the Author
My life is not only connected with cars, namely repair and maintenance. But I also have hobbies like all men. My hobby is fishing.
I started a personal blog where I share my experience. I try a lot of things, various methods and ways to increase the catch. If interested, you can read. Nothing more, just my personal experience.
Attention, only TODAY!
This article will discuss another interesting property of the oil. Namely about sulfate ash content of oil(do not be afraid of the wording, in fact, everything is simple). Then everything will be in human-understandable language.
Sulphated ash content of oil (according to science)
Of course, if you try to be imbued with scientific formulations and descriptions of the sulfate ash content of oil (hereinafter simply - the ash content of oil (although this is a different indicator, it makes no sense to separate them)), then all the desire to be interested in such issues in general disappears.
For example, this is how the description of the ash content of oil looks like on a rather nice and interesting resource www.mssoil.ru:
Sulfate ash content (sulfate slags) is an indicator for determining additives, including organic metal compounds. The ash formed during the combustion of oil with additives is treated with sulfuric acid to convert metal oxides into sulfates, which are calcined at a temperature of 775 ° C until sulfate ash is formed.
As they say, you can't figure it out without half a liter. But, you can go from the human side, and simplify everything.
Sulphated ash content of oil for humans. What you need to know and how to use it.
The simplest and most concise explanation of the ash content of oil looks like this: Sulphated ash content of oil is an indicator of the presence of additives in the oil. Confused for good? I unravel.
Everyone knows that oils (and all of them - both motor, and transmission, and any) consist of a base oil and a package of additives that determine the specifics of the oil's use. It’s easier - if you add different additive packages to the same base oil, then in one case we get (for example) top quality engine oil, and in the other - gear oil - simpler.
Which side to lean here oil ash content? Here it just shows that the oil contains a package of additives for “oil wrapping”, or tuning, so to speak.
The fact is that you can’t endlessly “tuning” the oil. Just because all these additives and additives are produced during the operation of the oil, respectively, they burn out, forming the very ash that can be seen on pistons, valves and rings. And, if he is responsible for the ability to neutralize all this, then sulfate ash content oils limits the ability of the oil to accumulate ash compounds.
The whole joke is that a large amount of ash will sooner or later begin to change the flash point of the oil, since the ash itself, having gathered somewhere (as always, in the most interesting place, on candles, for example) will ignite the combustible mixture earlier than expected, or vice versa, interfere with the same candles quality work.
That is why the presence of additives is limited, and their presence in the oil is illuminated by the same sulfate ash oil. With all other equal characteristics of the two oils, the one in which the sulfate number is higher wins, because. indicates a greater "tuning" of the oil.
Sulphated ash example
Even, rather, not an example, but a unit of measurement of the ash content of oil. In short, yes. The base oil is practically ashless; for powerful truck diesel sulfate ash oil limited by regulatory documents to 2% of the amount of oil, for a simpler diesel it is 1.8%, for a gasoline engine 1-1.5%.
The requirements of environmental legislation Euro 4 and Euro 5 forced car manufacturers to find such engineering solutions that would reduce the amount of harmful emissions into the atmosphere. For this, special exhaust gas aftertreatment systems have been developed. They were particulate filters and catalytic converters. To prolong the life of these filter elements, engineers have thought about how to clean them without removing them. Every modern exhaust aftertreatment system successfully cleans itself by simply burning soot, but it cannot defeat ash, which contains a lot of solid non-combustible particles. As a result, particulate filters and catalytic converters become clogged with ash and cease to perform their functions, as indicated by the on-board computer. Buying new filter elements is quite expensive. In order for motorists to avoid unnecessary costs, car manufacturers strongly recommend that they use low-ash oils that do not have solid particles in working out, therefore they do not clog after-treatment systems and do not wear out the engine.
How do low-ashers differ from classic motor oils?
LowSAPS or MidSAPS products are the latest generation engine oils based on new technologies. In Low SAPS oils, the content of sulphated ash does not exceed 0.5%. SAPS stands for SA (sulphated ash), P - phosphorus, S - sulfur. The abbreviation literally translates as: low levels of sulfate ash, phosphorus and sulfur.
The formulation of low ash oils differs in composition from classic full ash products. The base oil for MidSAPS and LowSAPS is more refined than is required for FullSAPS. And in low-ash oils, completely different additives are used. They have reduced the number of components containing SA (sulphated ash) - ash, P - phosphorus, S - sulfur. Tests have proven that low-ash oils provide excellent engine protection and also prevent the risk of premature wear due to the ingress of solid non-combustible particles. Scratches on engine parts often occur precisely because metal fireproof residues of full-ash classic oils get into it.
Low SAPS and classifiers: how to recognize low ash oil
Some motorists believe that oils corresponding to the CJ-4 class in the American API system are LowSAPS. But they are wrong. Oils of the CJ-4 group are more environmentally friendly than FullSAPS, but it is wrong to classify them as low-ash oils, since the amount of ash in them is at least 1%, and not 0.5%, as it should be in LowSAPS products. When choosing low-ash oils, it is better to focus on the European classifier ACEA. All oils of classes E9, C2, C3 fully comply with the characteristics of low-ash oils. It is also worth noting that certification in organizations such as the American Petroleum Institute or the Association of European Automobile Manufacturers is not at all mandatory for auto oil manufacturers. For them, the approvals and recommendations of automakers are much more important. If they are obtained, and the oil is labeled LowSAPS, then the product can be considered low-ash.
MidSAPs and LowSAPS oils: pros and cons
MidSAPs and LowSAPS oils have their pros and cons. Both of them, in their opinion, have an iron argument and irrefutable evidence of their innocence.
What arguments do opponents of LowSAPs oils use?
Fans of FullSAPS believe that additives in low-ash bins are "cut down". That is, all the components that protect the engine from wear perform their functions only for a while, and they will last no more than 7 thousand km. run. Then the oil needs to be changed immediately. What are these motorists looking for? For the content of zinc, calcium and molybdenum in additives. They simply compare the characteristics of old-type motor oils with new ones and say, they say, look, in the new LowSAPS and MidSAPS oils, the content of zinc, calcium and molybdenum is reduced, and these components protect the engine from wear. If so, then low-ash oils protect the motor much weaker. There is logic in such reasoning. But at the same time, opponents of LowSAPS do not take into account the fact that low-ash oils are developed using a completely different technology, the additives in them are different, and they provide excellent engine protection, but in a completely different way. It is worth considering that engine wear when using LowSAPS oils will be much lower, because metal particles that are so rich in FullSAPS oils will not get into the engine.
According to modern requirements, each exhaust gas aftertreatment system must be able to self-clean, that is, burn soot. However, it is not so easy to deal with ash containing a large amount of solid non-combustible particles. Ultimately, catalytic converters and particulate filters become clogged with ash and cannot do their job, and acquiring new parts is an expensive pleasure. To avoid unnecessary material waste, automakers strongly advise using only low-ash oils that do not leave solid elements after working out. But what does full ash, low ash or medium ash oil mean? Let's figure it out.
What is sulfate ash content of oil
One of the important parameters of engine oil is its sulfate ash content(or slag). In simple terms, this is an indicator that helps determine additives that include organic metal compounds. The ash remaining after the combustion of oil with additives is specially treated with sulfuric acid, which makes it possible to avoid metal oxides into sulfates, which are pierced at a temperature of 775 ° C, up to the formation of sulfate ash. That is, sulfate ash content of oil is an indicator of the presence of additives in the oil.
Interesting!The base lubricating fluid is practically ashless, and for a powerful truck diesel engine, this figure is limited by regulatory documents in the amount of 2% of the amount of oil.
Types of oils by ash content
Based on the amount of ash in the composition of the lubricating fluid, three types of oils are distinguished: low-ash, medium-ash and full-ash oils. But how to decide which one is better to fill in your car?
Full Ash Oils
First, let's try to figure out what full-ash oil is. First, you need to know that such fluids are marked as ACEA A1/B1, A3/B3, A3/B4, A5/B5 and can have a very negative effect on the DPF filters that are part of the EGR afterburning system, as well as on three-way catalysts. The ash content of full-ash oils is 1-1.1% of the total mass and such fluids are not recommended for use in engines equipped with Euro 4, Euro 5 and Euro 6 environmental systems.
Medium ash oils
Medium ash oil is designed and used in four-stroke gas engines equipped with a turbocharger. The good quality of this lubricating fluid helps to increase the interval between lubricant changes and prevents corrosive processes. In addition, it is medium ash oil that helps control pollution that periodically appears in biogases and contains a large amount of hydrogen sulfide and halides. The ash content of "medium ash" is in the range of 0.6-0.9%.
Low ash oils
Low-ash motor oils for gasoline engines differ from other types in their low ash content and its specific composition. The base oil for the production of this type of fluid is very carefully refined and supplemented with additives that are not typical for the above products. In particular, in low-ash oils, the amount of components containing ash, phosphorus and sulfur is significantly reduced, and the ash content does not exceed 0.5%.
The ongoing tests of low-ash lubricating fluids have proven that they are able to perfectly clean the engine, thereby preventing its premature wear, which is caused by the ingress of solid, non-combustible particles into the mechanism. By the way, scratches on the motor appear precisely as a result of exposure to metal fireproof residues of classic oils.
We can say that the low-ash version of lubricating fluids is an excellent lubricant for vehicles with modern exhaust gas aftertreatment systems, which is especially important for diesel engines.
Note!The biggest disadvantage of low-ash oil is that one filling with burnt fuel can "kill" all its useful properties.
How to find out what ash content of oil
If you do not know what oil with what ash content is used on your vehicle, then you can find out based on its tolerance. ACEA A3- These are full-ash lubricating fluids, ACEA C3 and C2- medium ash, and C1, C2, C3, C4- belong to the category of "little ashers".
General purpose, non-thickened oils that belong to the SE/D group typically have a sulphated ash content of about 1.0% The total additive content of such fluids is about 10.3-11.5%.
If you need, for example, full-ash oil, but you don’t know how to determine it, then you can heed the advice of experienced motorists. According to them, an oil that belongs to SAE 0-40, 5-40, or even higher, in almost no way can be a low-ash composition.
The lowest ash oils are used to lubricate parts in two-stroke gasoline engines, as well as gas-powered power units. The minimum ash content in the oil largely depends on the quality of the liquid purification: the better it is purified, the lower its ash content will be. In addition, this indicator may change with the introduction of additives containing organometallic compounds into the oil. Because of this, in some GOSTs, the value of zoning is noted before their addition and after mixing with additives.
Interesting fact!The ash content of the oil is limited by regulatory documents only in production in Europe (ACEA classification).
Sulphated Ash and Flash PointSulphated ash content is exactly the indicator that determines the amount of metal-containing additives in the lubricant for the motor. The more of them, the higher the ash level will be. But you need to understand that both an excess and an insufficient amount of such additives can harm engine oil, as they become a source of low-temperature deposits on the elements of the power unit. Probably, it was this fact that caused the appearance of a trend towards a decrease in sulfate ash content (even below 1.5%).
If engine oil is heated, then its vapors will form a certain mixture with air, and when a certain temperature is reached, it ignites. This temperature value is called the "flash point". First of all, its appearance is associated with the fractional composition of the oil and the structure of the molecular particles of the base components.
In most cases, a high flash point is still preferable, but if the oil is diluted by fuel due to engine failure, then it will decrease significantly. Together with a decrease in viscosity, a decrease in flash point should serve as a signal for troubleshooting in the carburetor, fuel supply system or ignition system. You can not constantly add various additives to the oil, since they are all produced during the operation of the car and form ash, which is easy to notice on the valves, rings and pistons of the power unit. If we take into account that the alkaline number of the oil is responsible for neutralizing all this “dirt”, then the sulfate ash content of the lubricant will limit the ability to accumulate ash compounds.
Over time (sooner or later), a large amount of ash will begin to change the temperature of the said oil flash, since the collected ash itself will begin to ignite the combustible mixture ahead of time, or, conversely, interfere with the high-quality robot of spark plugs and other elements. It is for this reason that manufacturers are trying to limit the presence of additives in the oil, which illuminates the sulfate ash content. As for all other characteristics, among all types of oil, liquids with a large sulfate number win (indicates a large "tricked out" lubricant).
What ash content is best for oil
As detergent additives added to motor oil, sulfonates, calcium or magnesium phosphonates, alkyl salicylates and alkyl phenolates are used. The correct combination of all ash additives with each other, and their interaction with ashless dispersant additives, helps to reduce low-temperature deposits in the power unit. In addition, this has a positive effect on the rate of contamination of oil filters.
Modified versions of ashless dispersants help reduce the formation of carbon deposits on pistons and rings, and metal-containing additives increase the ash content of the oil, which often leads to the formation of ash deposits in the combustion chamber, premature ignition of the fuel mixture, the appearance of a short circuit in the electrodes of spark plugs, burnout of exhaust valves and reduced fuel resistance. to detonation. Therefore, the sulfate ash content of motor oils is limited by the upper limit, and its permissible value will depend on the design features of the motor, its operating conditions (including the type of fuel used) and oil consumption for waste.
Important!In lubricants intended for gasoline power units, the sulfate ash content should not exceed 1.5%, for diesel enginesWithlow power - 1.8%, and for high power diesel engines - 2.0%.
Ash, as well as phosphorus and sulfur, which are contained in the exhaust gases, have an extremely negative effect on the operation of the converter, ultimately rendering it unusable. The particulate filter cells also suffer, being forgotten by all polluting deposits. In order to somehow solve this problem, SAPS oils were developed, where the letters of the name themselves indicate a limited content of sulfate ash (Sulphated Ash), sulfur (Sulphur), phosphorus (Phosphorus). The use of SAPS lubricating fluids makes it possible to increase the service life of the cleaning system up to 100,000 kilometers, which is very important, especially when you consider that a catalyst that contains expensive metals is quite an expensive pleasure.
So, now you know what oils exist according to the type of ash content, and you can probably decide whether you need a full-ash or low-ash version. Many car owners are more inclined towards low-ash oils, but whether this is good or bad depends only on the type of your engine and its design features, which should not be forgotten.
Hardly anyone will argue with the fact that the main purpose of motor oils is engine cooling. However, along with the development of the automotive industry, the range of tasks of these lubricants is expanding. Modern engine oils should perform not only cooling and protective functions, but also be responsible for reducing harmful emissions, energy saving, additional protection for turbocharged engines, etc.
Today there are about 1 billion cars on our planet. Every minute 200 cars are produced in the world. On average, there are 0.43 cars per 1 thousand inhabitants. At the same time, the car fleet is growing faster than the population of the Earth. The leaders in the production of vehicles in terms of per capita are the United States and, oddly enough, Luxembourg.
It is believed that there is no full-fledged alternative to the internal combustion engine for the coming decades. According to forecasts for the development of the passenger car fleet in the EU, gasoline engines will prevail, but the share of diesel engines is also growing - at the moment they are more than 37%. At the same time, diesel engines are not at all popular in the USA, where they account for only 2%.
With rising prices for gasoline and diesel fuel, the trend towards switching engines to gas is increasing. The production of hybrid engines is also beginning to progress. By 2015, experts predict the mass introduction of a mixed fuel supply system: gasoline / diesel.
Extremely important indicators of the quality of motor oil are its sulfate ash content and high temperature shear viscosity.
Sulfate ash content is an indicator that determines the amount of metal-containing additives in the oil. The more such additives, the higher the ash content. However, an excess, as well as an insufficient amount of additives, harms engine oil, as it becomes a source of additional low-temperature deposits on the engine: sludge, tar, coke. Today, in the production of motor oils, there is a clear trend towards a decrease in sulfate ash content - below 1.5%. In the meantime, most modern cars use low-sulphur fuels.
The ash content, as well as sulfur and phosphorus contained in the exhaust gases (EG), severely disable the exhaust gas converter and clog the cells of the particulate filters. SAPS oils were developed to solve this problem. In this abbreviation, the letters indicate the limitation in the oil of sulfated ash (Sulphated Ash), phosphorus (Phosphorus) and sulfur (Sulphur). The use of SAPS oils makes it possible to increase the service life of cleaning and neutralization systems up to 100,000 kilometers. This is especially important due to the fact that a catalyst containing expensive metals (platinum, ruthenium, palladium) is not cheap.
As you know, the main wear is on the cylinder-piston group and the crankshaft. The CPG accounts for 60% of wear, the crankshaft - 40%. That is why another fundamentally important indicator of oil quality is HTHS, or high temperature shear viscosity. In the engine, this oil parameter is essentially similar to the operation of crankshaft bearings. HTHS is measured in mipascals per second.
Today, there is a trend towards lower shear viscosity from the usual value of 3.5 mP/s. If the engine oil has a reduced HTHS, it can only be used in new engines prepared for this. The use of low HTHS oils in engines not designed for this purpose can lead to accelerated engine wear. It is explained simply. In engines adapted for low HTHS oil, the distance between the friction surfaces is extremely reduced, the parts fit so tightly that the gap is minimal.
If the precision pairs of the traditional sample (i.e. the gap is greater than necessary), the oil film breaks and metal-to-metal contact occurs. Currently, low HTHS oils are used in a number of VW models, as well as on some BMW and MB models. This contributes to additional fuel economy. However, in most modern models, oils with a standard HTHS value are still used.
In the modern world, there is an increasing tightening of environmental standards, since cars account for up to 60% of all harmful emissions into the atmosphere. Automobile exhaust contains up to 200 chemical compounds, the most harmful of which are carbon monoxide, hydrocarbon compounds, sulfur, phosphorus and, finally, particulate matter, i.e. soot. Soot is produced mainly by heavy diesel engines. Formally, this is pure carbon, which, it would seem, is not dangerous for the environment. But when exhausting gases, it acts as an absorbent of harmful compounds: absorbing them, it accumulates carcinogens.
The introduction of an exhaust gas recirculation system has led to new requirements for engine oils.
Recirculation - the supply of part of the exhaust gas back to the engine - made it possible to reduce the content of nitrogen oxides in the exhaust gas. However, due to recirculation, the crankcase oil temperature increased, on average from +120 °C to +130 °C. Therefore, engine oil must have enhanced antioxidant properties. Otherwise, with a decrease in nitrogen oxides, soot emissions will increase. The solution was found in the form of ashless additives based on nitrogen and manich bases. Their use made it possible to maintain the required amount of metal-containing additives without harm to exhaust gas cleaning systems.
The operation of the oil directly depends on the quality of the fuel. In order for modern oil to work efficiently, the sulfur content in the fuel should not exceed 0.005%.
The oil change interval (its aging period) is increased due to antioxidant additives. Change intervals are determined by the automaker, so its recommendations should be heeded regardless of which oil is used. However, it is important to know that the interval also depends on a number of subjective factors. For example, in the urban cycle or the use of high-sulfur fuel, it is shortened by almost half. In addition, it is known that 80% of engine wear occurs in the last 20% of oil operation. And this means that it is better to change the oil a little earlier than recommended.
Reducing fuel consumption is one of the main tasks set by car manufacturers. To this end, they improve aerodynamics, reduce weight through the use of cermets, aluminum and other lightweight materials. Work is also underway to reduce tire rolling resistance and develop new transmission designs to reduce torque losses. But the main efforts are focused on improving the engine: the development of new injection systems, new energy-saving motor oils.
