Classification of motor oils API(American Petroleum Institute) is widely recognized as setting minimum performance standards and quality levels for oils for gasoline and diesel engines... This classification has been significantly improved as quality requirements have increased. lubricants, which, in turn, was caused by a significant improvement in engine technology, which also entailed an increase in the power of engines of these sizes, an improvement in the quality of the metal from which engine parts are made and an increase in mechanical strength, as well as, of course, an increase in operating loads.

Motor oils for gasoline engines are designated in this classification by the letter S (service station), and the categories range from (lightest duty oils with little or no additives) to the most recent category (oils for today's powerful, multi-valve engines, often turbo and supercharged). Oils for diesel engines differ in a similar range of categories, where the category name begins with the letter C (commercial)... This includes categories from to. These are oils designed to work in the latest diesel engines and under modern operating conditions.

Below is a brief description of all categories in their evolutionary development in terms of service classifications of American Petroleum Institute engine oils. Where the obsolete category is marked, it means that the category has been replaced by a new category.

Performance Standards APIare specified using the abbreviations API SJ and API CE:
... the first letter denotes the type of engine (S \u003d petrol and C \u003d diesel)
... the second letter denotes the performance level, and the lower the performance level, the higher the letter in the alphabet.

PETROL ENGINES

API SG
Oils for use in gasoline engines 1989. For use in modern gasoline engines passenger cars, vans and light trucks serviced according to the manufacturer's recommended procedures. Oils formulated for this application provide improved protection against engine carbon deposits, oil oxidation and engine wear over previous grades, as well as protection against rust and corrosion. SG oils meet the requirements for diesel engines and can be used where a, SF / CC or SE / CC is recommended.

API SH
Oils for use in gasoline engines 1994. The category was adopted in 1992 to define the characteristics of engine oils recommended since 1993. For normal use in gasoline engines of the modern fleet of passenger cars, vans and light trucks, serviced according to the recommendations and instructions of the manufacturers. This category exceeds the requirements of the category and was developed to replace it in order to improve the anti-carbon, antioxidant, antiwear properties of oils and protection against rust and corrosion. API SH compliant oils in this category have been tested according to the requirements of the Chemical Manufacturers Association (CMA). The product is approved by the Code of Practice and can be used according to API recommendations for interchangeability of oil bases and viscosity grade performance testing. Oils in this category can be used where the category and earlier categories are recommended.

API SJ
Oils for use in gasoline engines 1996. API SJ performance category characterizes engine oils sold on the market since 1996 SJ includes the same minimum ratings as the SH to be replaced, plus additional requirements for sludge control and performance at low temperatures during bench tests. Oils in this category are intended for normal use in gasoline engines of modern and older passenger cars and sports cars, vehicles, vans and light trucks serviced according to the recommendations and instructions of the manufacturers. Oils meeting API SJ requirements may be used where category and earlier categories are recommended.

API SL
Oils for car engines manufactured after 2000. For multivalve, turbocharged, lean-burn, with increased requirements for energy efficiency and environmental friendliness. Oils meeting the requirements of API SL, SM can be used in cases where a category and earlier categories are recommended.

API SM
The category was approved on November 30, 2004. In addition to the SL category, improved antioxidant and antiwear properties. Improved low temperature properties. Possibility of certification in the ILSAC energy efficiency category.

API SN
The category was approved on October 1, 2010. Designed for oils used in the most modern gasoline engines of passenger and sports cars and small vans. Oils of this category have improved antioxidant and detergent properties, provide high protection against wear and corrosion. Strengthened high temperature properties for operation in turbocharged engines. They can be used where the use of oils of categories SM and SL is recommended. Some oils in this category may meet the ILSAC GF-5 specification and qualify as energy efficient.

EU API
Gasoline Energy Saved ™ Classifications - EU 1995. There are two grades that define the category of gasoline engine oils designed to improve fuel economy. TECU stands for oils that improve fuel economy during standard tests by at least 1.5% compared to conventional oils, and TEC-IIU - at least 2.5%

DIESEL ENGINES

API CE
Oils for use in diesel engines 1983 (obsolete category). For use in certain powerful engines turbocharged with additional compression, manufactured since 1983 and operating at high loads at both low and high shaft speeds. They can also be used in conditions for which the category oils are recommended.

APICF
Used in diesel engines with indirect injection - CF 1994. Typical use for diesel engines with indirect injection, as well as other types of diesel engines using various fuels, including those with a higher sulfur content (for example, more than 0.5% by weight ). CF oils are effective in preventing piston deposits, wear and corrosion of copper-bearing bearings, which are essential for these types of engines, and can be sucked up in the usual way, supplied with a turbocharger or a supercharger. Oils of this technical category can be used instead of oils.

API CF-4
Oils for use in diesel engines 1990 For typical applications in four-stroke diesel engines running on high speedswhere the requirements exceed the capabilities of the category and use instead of oils of the CE category is required. Provides improved oil consumption and piston carbon deposits. Particularly effective in diesels powerful tractors and vehicles on the highway. In combination with the corresponding category, they can be used in gasoline engines if recommended by the manufacturer.

API CF-2
Used in Heavy Duty 2-Stroke Diesel Engines - CF-2 1994 Typical use for two-stroke enginesthat need highly effective prevention of cylinder and ring abrasion and deposits. has improved performance and can be used instead of other materials if necessary.

APICG-4
The category was introduced in 1995. Oils designed for high-load, high-speed, four-stroke diesel engines trucks mainline type using fuel with a sulfur content of less than 0.05% by weight and non-mainline type (sulfur content can reach 0.5% by weight). Effectively suppress the formation of high-temperature carbon deposits on pistons, wear, foaming, oxidation, soot formation (these properties are necessary for engines of new mainline tractors and buses). The category was created to meet the requirements of the United States exhaust gas emission standards (1994 revision). Replaces oils of categories, and. The main drawback limiting the use of oils of this category in the world is the relatively large dependence of the oil resource on the quality of the fuel used.

APICH-4
The category was introduced on December 1, 1998. Oils of this category are intended for high-speed, four-stroke engines meeting the requirements of the stringent 1998 standards for exhaust gas toxicity. They meet the highest requirements of not only American but also European diesel engine manufacturers. Specially formulated for use in engines using fuels with a sulfur content of up to 0.5% by weight. In contrast to the category, the use of diesel fuel with a sulfur content of more than 0.5% is allowed, which is an important advantage in countries where high-sulfur fuels are common (South America, Asia, Africa). The oils meet the increased requirements to reduce valve wear and carbon deposits. Replace oils of categories,, and.

APICI-4
Category introduced since 2002 . An oil corresponding to this level has higher dispersing properties (the amount of detergent-dispersing additives), has an increased resistance to thermal oxidation compared to the class, provides a decrease in oil consumption for waste by reducing volatility and reducing evaporation losses under the influence of gases when operating temperature 370 ° C. Improved cold pumpability, increased service life of engine seals by improving oil compatibility with them. The class was introduced taking into account the tightening of requirements for the environmental characteristics of motors produced from October 1, 2002.

API CI-4 PLUS
Service category for diesel engines with more stringent soot requirements. Upon receipt of this classification, the engine oil is tested in 17 motor tests.

API GL-3
Oils for gears operating in moderate conditions. Contains up to 2.7% antiwear additives. Designed for lubrication of cone and other gears of trucks. Not meant for hypoid gear.

API GL-4
Oils for gears operating in conditions of varying severity - from light to heavy. Contains 4.0% effective extreme pressure additives. Designed for bevel and hypoid gears with small axle displacement, for gearboxes of trucks, for drive axle units. API GL-4 oils are designed for non-synchronized gearboxes of North American trucks, tractors and buses ( commercial vehicles), for main and other programs of all vehicles... Today these oils are also used for synchronized transmissions, especially in Europe. In this case, the label or data sheet of the oil must contain an inscription about this purpose and confirmation of compliance with the requirements of the machine manufacturers.

API GL-5
Oils for the heaviest gears operating in harsh conditions. Contains up to 6.5% effective extreme pressure and other multifunctional additives. The main purpose is for hypoid gears with significant axle displacement. They are used as universal oils for all other mechanical transmission units (except for the gearbox). For a synchronized manual transmission, only oils are used that have a special confirmation of compliance with the requirements of the machine manufacturers. Can be used for limited slip differentials as long as specifications are met MIL-L-2105D (in the USA) or ZF TE-ML-05 (in Europe). Then the class designation has additional signs, for example, API GL-5 + or API GL-5 SL. Oils for the most loaded gears operating in very difficult conditions (high sliding speeds and significant shock loads). Contains up to 10% of highly effective extreme pressure additives. Designed for hypoid gears with significant axle displacement. They correspond to the highest level of performance properties.

API MT-1
Oils for highly loaded units. Designed for unsynchronized mechanical boxes transmissions of powerful commercial vehicles (tractors and buses). Equivalent to oils, but with increased thermal stability.

API PG-2
Oils for transmission of drive axles of powerful commercial vehicles (tractors and buses) and mobile equipment. Equivalent to oils, but with improved thermal stability and improved elastomer compatibility.

For mechanical transmissions (except for hypoid ones), oils and are mainly used; for hypoid final drive: API GL-4 - for medium loaded gears and API GL-5 - for heavily loaded gears, including hypoid gears with significant axle displacement. Oil companies produce universal oils intended for both gearboxes with synchronizers and for heavily loaded hypoid gears.

Together with the SAE oil viscosity classification, the API determines its applicability to a particular engine. You can read what the API itself is and what other classifications are there.
For most modern gasoline engines, it is envisaged to use oil of the SL quality group if the engine was produced before 2004 or SM if after. In some places, if the year of manufacture is before 2001, the oil of the SJ group is allowed.
The reference books say the following:
“SJ - Oils for engines produced in 1996-2001. They contain less environmentally harmful impurities than SH group oils and have energy-saving properties.
SL - Oils for engines manufactured since 2001. They have significantly improved detergent, antioxidant, antiwear and energy saving properties, reduced volatility and good compatibility with exhaust gas converters.
SM - Oils for engines manufactured since 2004. Oils of this category meet the increased requirements of the new generation engine manufacturers. Replace oils of groups SJ and SL ”.
There is a new SN oil, but little information about it yet. It is clear that oils of the SN group can be considered the best today. And they are able to replace everything that was produced before. That is, if SJ oil is allowed in the instructions for the car, then SN is suitable for it.
For comparison, the most common and demanded groups SL and SM were selected
So, what would you like to have from an ideal oil? First, it must lubricate the parts ideally and optimally, and in all engine operating modes. This means - to reduce friction as much as possible, thereby increasing power and reducing fuel consumption. Secondly, to minimize wear and tear, thereby extending the life of the motor. Thirdly, to serve as long as possible, reducing the cost of replacing it. Fourth, to reduce the environmental damage from the motor, in the civilized world, this point is considered very important.
It is good to have some kind of harmony in the price-quality ratio.

AGING OIL

There are several reasons and factors for oil aging. An oil is a complex combination of hydrocarbon compounds, with different additives and impurities, called an additive package. In the combustion chamber, the remaining after moving the piston to the bottom dead center the oil film absorbs all the power of the heat flow, which gradually changes the structure and composition of the oil. After all, only a small part of this film burns out, and the rest, overheated, with volatilized light hydrocarbons, oxidized by contact with oxygen at high temperatures, is washed off into the engine sump. There is not much of this modified oil for a cycle - the thickness of the films is micron, but there are a lot of cycles. In bearings there is no such heating, maximum, up to 180 degrees, but the pressures are very high, reaching 30 ... 40 MPa. It also changes the properties of the oil. In addition, it comes into contact with hot and corrosive blow-by gases in the oil pan.
The oil should wash the engine - it washes it, but at the same time it is saturated with dirt, both mechanical and organic. Some of them will sit in oil filter, but something will remain in the oil volume. And, besides, this triggers the detergent components, an important part of the additive package.
For modern "synthetics" resources are declared large - 20 ... 30 thousand kilometers.

Aged motor tests

The more oil is fed into the cylinders, the faster it ages. Thicker oil films on the cylinder walls mean that more oil is thermally affected per cycle. And its volume in the crankcase is constantly decreasing - due to the big waste. The increased pressure of crankcase gases and their higher temperature also increase the rate of oil oxidation. And the sharply increasing amount of deposits in the old motor requires more - detergent additives.
Therefore, it is logical to speed up oil testing on an artificially aged engine. A special engine was assembled for testing, with normal bearing clearances and sharply increased cylinder piston group.

SL, SM

For testing, selected modern "synthetics", the same SAE, 5W40.
Now let's try to search different oils according to API classification. It would be correct if all oils were of the same brand, but different groups by API. But this, alas, does not happen - higher quality oil from all companies simply displaces its predecessor. Therefore, you have to choose from what is. But, to increase the reliability of the results, two oils are included in each comparison group.
The first sample is Esso Ultron oil (1100 rubles per canister), which has a transitional quality class SJ / SL. The second is BP Visco 5000 oil (1070 rubles per canister). From the SM family - the French Motul X-Clean 8100 (2810 rubles per canister). As a couple, they took a completely new Dutch oil NGN Gold (1,030 rubles per canister).
After each test cycle, the motors were disassembled, measured, and parts were weighed to determine wear and contamination.
After that, tests were carried out on a motor assembled taking into account all clearance requirements, practically new, unworn, and well-run. It ran standard test cycles sequentially, first for all fresh oils, and then for those “killed” by the resource cycle. And already here they measured the power, fuel consumption, and environmental parameters.
The first test cycle - on fresh oils, did not reveal much difference in the engine response to the API group - everything remained within the measurement error.
And the second cycle, on used oils, put everything in its place. Synthetic oils the SL groups sharply reduced their characteristics in comparison with their fresh samples, while the decrease was observed in Motul and NGN Gold to a much lesser extent. The difference between oils of different categories was already much more noticeable - up to 6 ... 7% in fuel consumption, up to 10% in toxicity, and 2 ... 4% in power between the Esso-Visco and Motul-NGN groups. Moreover, the motor reacted more than others to the aging of BP Visco oil.
The test results are summarized in the table:

This changes the working high-temperature kinematic viscosity of oils of various API groups. First - reduction, this is the destruction of thickening additives. And then - growth. This is a consequence of the decomposition and changes in the properties of the base oil. The less pronounced this process, the longer the oil resource.

In terms of viscosity, all oils are clearly within the range prescribed by SAE grade 5W40. The viscosity indices are very high, typical for good "synthetics" ("viscosity index" is a parameter indirectly responsible for the cold start of the engine).
Look at the content of the active elements. This is a direct characteristic of the additive package. What is striking here is that their concentrations in the starting oils, that of the SL and SM groups, are very close. Indeed, the vast majority of manufacturers use almost the same additive packages - there are few of them in the world. But the base for all oils is different, and the difference in numbers.
Sulfur content. Sulfur compounds hit catalysts hard. It is always present in oil - both from the base oil and is included in the EP and antiwear additives. Motul X-Clean proved to be the leader in oil purity from sulfur, and NGN Gold was the “leader” at the other end. But there are no regulatory restrictions on this parameter, and experience suggests that most oils have it above 0.5 ... 0.6% sulfur content.
Alkaline number. For all oils, it is quite high - this is a sign of detergency. But SM oils, and Motul X-Clean, and NGN Gold, it is lower. The more stable base of SM oils requires less detergent additives to maintain the required engine cleanliness, and the excess alkali in the oil is harmful - it increases the corrosiveness and reduces the life of the additives.
Analysis of the data obtained on used oils confirmed that, indeed, oils of the SM group are more stable. And this means - and their service life is longer.
Let's go back to the motor test data. Everything is confirmed by the results of "physical chemistry". Indeed, Motul X-Clean and NGN Gold gave a greater energy-saving effect - the engine, albeit a little, but became more economical, a little more powerful, and this effect persists and even increases with parallel operating time. But the main thing is that deposits in the engine itself, and in the oil pan, and on the valve mechanism, and on the pistons (and this is the most important thing), these oils gave much less. And the wear of parts is also less, and significantly. And this is again confirmed by "physical chemistry" - see the content of wear products.
IS IT WORTH PAYING MORE? So, the bottom line. Do I need to overpay for modern SM oils? For those who have a direct indication of SM oils in the instructions, this question has an unambiguous answer. The rest have a choice.
Of course, oils of the SL class are also high quality, but SM really have certain "pluses". This is both better protection of the motor from wear, and a lower level of deposits in the motor, and a longer service life.
The specific figure after what mileage it is necessary to change oils of one and another class is a purely individual parameter that depends on both the brand of the engine and its technical conditionand the quality of the fuel used and the driving style. But according to estimates - good oils SM groups will give SL oils 30 ... 40 percent handicap in terms of resource.

Opening the engine and weighing the parts after testing each oil made it possible to assess their protective capabilities. SM oils are indeed more effective in reducing wear - this was confirmed by our experiment.

Table 1 PHYSICAL AND CHEMICAL INDICATORS OF ENGINE OIL SAMPLES

In the numerator, the indicators determined in the initial oil samples after the first test cycle (after 6 engine hours), in the denominator - in the final samples (after 120 engine hours)

AVERAGE ENGINE PERFORMANCE INDICATORS OBTAINED WHEN OPERATING WITH VARIOUS ENGINE OILS

In the numerator, the indicators determined for fresh oil, in the denominator, for the final oil samples (after 120 operating hours)
Deterioration in indicators is highlighted in red, improvement in green, and change within the measurement error in blue.

The mass of deposits on the control weighing elements at the end of the test cycle

Deposits on the side of the piston are the most dangerous! They can lead to stuck rings - and hence the loss of compression and overheating of the piston. Completely killed mineral oils give approximately such deposits.

And such - oils of the SL group ...

And these are the SM groups. The difference is noticeable

There are also deposits in the crankcase after SL oils, their presence is inevitable

This is how the same crankcase looks after SM oil

The difference is not so noticeable on valve mechanisms, but it is also there .. This is after the oil of the SL group

It's after SM group oil

Types of engine oils - Decoding engine oil

The oil, which is called "synthetic" (usually referred to as Fully Synthetic on the box), has a synthetic base obtained by synthesizing chemical elements. The main differences between "synthetics" are the ability to set a number of parameters in advance, even when creating an oil base, as well as the maximum content of various additives. Therefore, these oils often provide better protection and detergent properties, do not thicken very much in severe frosts, withstand maximum operating temperatures.

« Mineral water”(Often marked on the box as Mineral), oil with a mineral base obtained from petroleum through its processing, it is much cheaper. However, such oil does not provide the same maximum operational results as "synthetics" - it does not withstand such high temperatures, thickens more in the cold, oxidizes faster and requires replacement, when boiling, it leaves slags in the engine.

« Semisynthetics"(Semi-Synthetic designation) is a kind of golden mean between the two previous types of oils. Often, semi-synthetics are created on a mineral basis, but with the addition a large number various additives that bring the performance properties of this oil closer to "synthetics". Moreover, "semisynthetics" are somewhat cheaper than "synthetics".

Motor oil has two main parameters, according to which its classification is carried out - the area of \u200b\u200bits application (diesel engine, old gasoline engine, modern turbodiesel, etc.) and viscosity-temperature properties. Despite the different bases of oils, they are all classified according to the same standards. Today the most popular classifications are SAE and API.

Viscosity-temperature properties are classified only by SAE (Society of Automotive Engineers) - in other words, it is the SAE index that regulates how "thick" or "liquid" this oil is. Most oils today are “universal” oils, i.e. suitable for both winter and summer use. Their SAE class is written in two numbers separated by a hyphen, with a letter in between W - for example, 10W-40. The letter W means that this oil is suitable for winter use, and the number in front of it is an indicator of low-temperature viscosity (roughly speaking, how cold this oil will withstand). The second number is an indication of the high temperature viscosity (i.e. how much summer heat the oil can withstand). However, if the oil is only suitable for summer use, then its designation will look, for example, as SAE 30.

Engine Oil Decoding - SAE Numbers

Low temperature viscosity readings mean the following:

* 0W - the oil is suitable for use in frosts down to -35-30 degrees. WITH
* 5W-oil is suitable for use in frosts down to -30-25 degrees. WITH
* 10W - oil is suitable for use in frosts down to -25-20 degrees. WITH
* 15W - oil is suitable for use in frosts down to -20-15 degrees. WITH
* 20W - oil is suitable for use in frosts down to -15-10 degrees. WITH

High temperature viscosity readings mean the following:

* 30 - the oil is suitable for use in heat up to + 20-25 degrees. WITH
* 40 oil is suitable for use in heat up to + 35-40 degrees. WITH
* 50 oil is suitable for use in heat up to + 45-50 degrees. WITH
* 60 oil is suitable for use in heat up to +50 degrees. From and above

The lower the number - the "thinner" the oil, the larger the number - the thicker it is. Thus, 10W-30 oil can be used at ambient temperatures from -20-25 degrees below zero, up to + 20-25 degrees of heat.

Engine Oil Decoding - API Numbers

The area of \u200b\u200bapplication of the oil is classified mainly by API (American Petroleum Institute) - the API designation is put in two letters (for example, SJ or CF), the first of which indicates the type of engine: S-gasoline engine, C-diesel. The second letter specifies the conditions for using the oil - a modern engine or an old one, with or without a turbine. If the oil is designated API SJ / CF, it means that it is suitable for both gasoline and diesel engines of this category.

API designations for gasoline engines:

* SC - cars developed before 1964
* SD - cars developed in 1964-1968
* SE - cars developed in 1969-1972
* SF - cars developed in 1973-1988
* SG - cars developed in 1989-1994, for severe operating conditions
* SH - vehicles developed in 1995-1996 for severe operating conditions
* SJ - cars developed in 1997-2000, better energy saving properties
* SL - cars developed in 2001-2003, extended service life
* SM - development vehicles since 2004, SL + improved oxidation stability

When changing the type of oil, according to the API classification, you can only go "ascending", and change the class only by a couple of points. For example, instead of SH, use SJ, usually a higher grade oil already contains the necessary additives of the "previous" oil. However, for example, you should not switch from SD (for old cars) to SL (for modern cars) - the oil may turn out to be too aggressive.

API Designations for Diesel Engines:

* CB - cars before 1961, high sulfur content in fuel
* CC - vehicles up to 1983 working in severe conditions
* CD - cars before 1990, high sulfur fuel and difficult working conditions
* CE - cars before 1990, turbine engine
* CF - cars from 1990, with a turbine
* CG-4 - cars from 1994, with turbine
* CH-4 - cars since 1998, under high US emission standards
* CI-4 - modern cars, with turbine, with EGR valve
* CI-4 plus - similar to the previous one, under high US toxicity standards

In Europe, the ACEA (European Auto Manufacturers Association) oil classification is often used. In part, the requirements for oil quality overlap with API requirements, however, they are more stringent in a number of parameters. Oils for gasoline and diesel engines are designated by the letter combination "A / B" with a specific number after the letter. And the higher this figure, the higher the requirements for the oil: for example, oil with the ACEA A3 / B3 class also has the API SL / CF class. However, using highly loaded turbocharged compact motors, Europeans are forced to develop special oils with maximum protective properties and minimum viscosity (in order to reduce friction losses and improve environmental performance). For example, oil of ACEA A5 / B5 class may be “steeper” than API SM / CI-4 in a number of parameters.

There is also an ISLAC oil classification (an international committee created by the Americans and Japanese), however, all ISLAC quality standards intersect with API standards. So, ISLAC GL-1 oils are used for gasoline engines and comply with API SH oils, ISLAC GL-2 oils are used in gasoline engines and comply with API SJ, but ISLAC GL-3, as you might guess, is used in gasoline engines and comply API SL. Also for Japanese diesel cars JASO DX-1 specification oil may be required, which takes into account the stringent quality requirements of engine oils for modern environmentally friendly high-load Japanese turbodiesels.
Video: Are all engine oils the same?

Watch a video on choosing and changing engine oil.

Video: the composition of engine oil.

Video clip about a unique additive in motor oil.
http://www.youtube.com/watch?v\u003dJ6zt8_su3EQ

Tags: Engine oil decoding, SAE and API numbers.

The abbreviation API must be understood as the classification of API motor fluids, thanks to the specified system developed by the American Petroleum Institute, you can choose a mixture depending on the type of fuel used for the car and by the year of manufacture of the engine, taking into account its technical characteristics.

According to the standards of this system, motor fluids are divided into three classes:

• S (Service) includes mixtures for gasoline engines;
• C (Commercial), holds fluids for diesel engines;
• EC (Energy Conserving), includes energy-saving fluids with low viscosity, easy flowing, reducing fuel consumption.

Marking of each class of car oils consists of two letters of the Latin alphabet. The first indicates the type of fuel applicable to the car, the second indicates the quality characteristics of the engine mixture, the further in the alphabet the second letter is located, the better the properties of the oil. For engines powered by diesel fuel, the classes are additionally divided into four-stroke and two-stroke motors, subclasses are marked with Arabic numerals 4 and 2, respectively.

For universal motor oils (diesel and gasoline), double marking is used, for example, SF / CC, for which fuel the oil is more suitable is indicated by the first letter of the designation.

According to the API standard, there are classes excluded from the classification, but cars with old engines continue to need these classes, therefore, according to the specified system, the class that is an order of magnitude higher replaces the lower one.

In addition to the requirements for viscosity and tribological properties of mixtures, their influence on the exhaust gas cleaning system, interaction with particulate filters... For engines with neutralizers, particulate filter elements, categories of liquids with a reduced amount of sulphated ash, phosphorus and sulfur are used.

You can learn more about the API specification by watching the video:

Classes for gasoline engines

Table 1 shows the classification of S-labeled engine mixtures.

Table 1. Motor oils for petrol-powered drives.

Diesel Drive Specification

Table 2 shows the specification of API engine fluids with C marking.

Table 2. Motor oils for diesel-powered drives.

Canister marking

Lubricants whose composition has been subjected to laboratory studies and meets API and SAE standards are marked with a graphic round sign that indicates the viscosity of the engine mixture and the quality category corresponding to the classification of engine fluids according to API.

This designation applies only to energy-saving liquids of the highest quality. For example, the sign shown in Figure 1 indicates: the fluid is all-season. Can be applied in temperature range -30 0 C to +25 0 C. At the same time, it will provide a cold start of the engine without warming up and pumping the mixture through the lubrication system, plus it will prevent the engine from overheating at a high positive temperature outside the car. These characteristics of an all-season mixture are indicated by the inscription SAE 5w-30. From the inscription API Service SN it follows: the engine oil is designed for the latest gasoline engines. It can be used for biofuel drives, they provide maximum environmental protection, long engine life. The inscription at the bottom of the sign indicates the energy-saving properties of the mixture and the extended replacement period.

When choosing an engine fluid, it is necessary to take into account the recommendations of the car dealer, since the oil is too thick or very liquid will not be able to protect the engine from wear: it will lead to dry friction of parts, and this is a direct way to overhaul power unit.

For engines japanese cars the ILSAC system is used, together with API, such fluids have a low consumption for waste, contain a minimum amount of phosphorus and sulfur. They can be used in engines equipped with exhaust gas filter elements.

The API (American Petroleum Institute) engine oil classification system was established in 1969. According to the API system, there are three operational categories (three rows) of purpose and quality of engine oils:

S (Service) - consists of quality categories of motor oils for gasoline engines, in chronological order.
C (Commercial) - consists of the categories of quality and purpose of oils for diesel engines, in chronological order.
EC (Energy Conserving) - energy saving oils. New row high-quality oils, consisting of low-viscosity, low-flowing oils that reduce fuel consumption in gasoline engine tests.

For each new class, an additional letter is assigned alphabetically. Universal oils for gasoline and diesel engines are indicated by two symbols of the respective categories: the first symbol is the main one, and the second indicates the possibility of using this oil for a different type of engine. Example: API SM / CF.

API quality classes for gasoline engines

API SN class - approved on October 1, 2010.
The main difference between API SN and previous API classifications is in limiting the phosphorus content for compatibility with modern exhaust gas aftertreatment systems, as well as comprehensive energy saving. That is, oils classified by API SN will approximately correspond to ACEA C2, C3, C4, without correction for high-temperature viscosity.

API SM class - approved on November 30, 2004.
Motor oils for modern gasoline (multivalve, turbocharged) engines. Compared to the SL class, engine oils that meet API SM requirements must have better protection against oxidation and premature wear of engine parts. In addition, standards have been raised regarding oil properties at low temperatures. Engine oils of this class can be certified according to the ILSAC energy efficiency class
Engine oils that meet the requirements of API SL, SM can be used in cases where the car manufacturer recommends class SJ or earlier.

API SL class - motor oils for engines of cars manufactured after 2000.
In accordance with the requirements of car manufacturers, motor oils of this class are used in multivalve, turbocharged engines running on lean fuel mixtures that meet modern increased environmental requirements, as well as energy saving. Automotive oils that meet API SL requirements can be used in cases where the car manufacturer recommends the SJ class or earlier.

SJ API class - engine oils for use in gasoline engines since 1996 release.
This class describes motor oils that are used in gasoline engines since 1996. Motor oils of this class are intended for use in gasoline engines of cars and sports cars, vans and light trucks, which are serviced in accordance with the requirements of car manufacturers. SJ has the same minimum standards as SH, plus additional carbon and low temperature requirements. Engine oils meeting API SJ requirements can be used when the vehicle manufacturer recommends SH class or earlier.

API SH class- motor oils for gasoline engines since 1994.
The class was adopted in 1992 for engine oils recommended since 1993. This class is characterized by higher requirements compared to the class SG, and was developed as a substitute for the latter, to improve the anti-carbon, antioxidant, anti-wear properties of oils and increased protection against corrosion. Motor oils of this class are intended for use in gasoline engines passenger cars, vans and light trucks, in accordance with the recommendations of their manufacturers. Engine oils of this class have been tested in accordance with the requirements of the Chemical Manufacturers Association (CMA). Engine oils of this class can be used when the vehicle manufacturer recommends class SG or earlier.

API SG class- motor oils for gasoline engines since 1989.
Designed for use in gasoline engines of passenger cars, minibuses and light trucks. Motor oils of this class have properties that provide improved protection against carbon deposits, engine oil oxidation and engine wear, in comparison with previous classes, and also contain additives that protect against rust and corrosion of internal engine parts. SG engine oils meet API CC diesel engine oils and can be used where SF, SE, SF / CC, or SE / CC are recommended.

API SF class- motor oils for gasoline engines since 1980 (obsolete class).
These engine oils were used in gasoline engines from 1980-1989, subject to the recommendations and instructions of the engine manufacturer. Provide enhanced oxidation stability, improved wear protection of parts, in comparison basic characteristics motor oils SE, as well as more reliable protection against carbon deposits, rust and corrosion. Engine oils of class SF could be used as replacements for previous classes SE, SD or SC.

API SE class - motor oils of gasoline engines produced since 1972 (obsolete class). These engine oils were used in gasoline engines produced in 1972-79, as well as some models in 1971. Additional protection in comparison with SC and SD motor oils and can be used as substitutes for these categories.

API SD class - motor oils for use in gasoline engines since 1968 (obsolete class). Motor oils of this class were used in gasoline engines of passenger cars and some trucks produced in 1968-70, as well as some models of 1971 and later. The improved protection compared to SC engine oils was also used only when recommended by the engine manufacturer.

API SC class - motor oils for gasoline engines, since 1964 (obsolete class). They were usually used in the engines of passenger cars and some trucks manufactured in 1964-1967. Reduces high and low temperature carbon deposits, wear, and also protects against corrosion.

API SB class - motor oils for low-power gasoline engines (obsolete class). Motor oils of the 30s of the 20th century, which provided fairly light protection against wear and oxidation, as well as anti-corrosion protection for bearings in motors that are operated under light load conditions. Engine oils of this class may only be used if specifically recommended by the engine manufacturer.

API SA class - motor oils for gasoline and diesel engines. An obsolete class of oils for use in older engines operating in conditions and modes in which protection of parts with additives is not needed. Engine oils of this class can only be used if they are recommended by the engine manufacturer.

API Grades for Diesel Engines

API class CJ-4- valid from October 1, 2006.
This class is specially designed for heavy duty engines. Meets key NOx and particulate emissions regulations for 2007 engines. For CJ-4 oils, limits are introduced for some indicators: ash content less than 1.0%, sulfur 0.4%, phosphorus 0.12%.
The new classification accommodates the requirements of the earlier API CI-4 PLUS, CI-4 categories, but introduces significant changes to the requirements in response to the needs of new engines that meet the new 2007 and later emission standards.

API Class CI-4 (CI-4 PLUS) - a new performance class of engine oils for diesel engines. Compared to API CI-4, the requirements for the specific soot content as well as volatility and high-temperature oxidation are increased. When certified in this classification, the engine oil must be tested in seventeen motor tests.

API Class CI-4 - the class was introduced in 2002.
These engine oils are used in modern diesel engines with different kinds injection and boost. An engine oil corresponding to this class must contain the appropriate detergent and dispersant additives and, in comparison with the CH-4 class, has increased resistance to thermal oxidation, as well as higher dispersing properties. In addition, such motor oils provide a significant reduction in engine oil waste by reducing volatility and reducing evaporation at operating temperatures up to 370 ° C, under the influence of gases. The requirements for cold pumpability have also been strengthened, the resource of clearances, tolerances and motor seals has been increased by improving the fluidity of the motor oil.
The API CI-4 class was introduced in connection with the emergence of new, more stringent requirements for the ecology and toxicity of exhaust gases, which are imposed on engines manufactured from October 1, 2002.

API class CH-4 - valid from December 1, 1998.
Motor oils of this class are used in four-stroke diesel engines that operate in high-speed modes and comply with the requirements of the norms and standards for exhaust gas toxicity adopted in 1998.
Auto aPI oils CH-4 meets the rather stringent requirements of both American and European diesel engine manufacturers. The class requirements are specially designed for use in engines running on high quality fuels with a sulfur content of up to 0.5%. Moreover, unlike the API CG-4 class, the resource of these engine oils is less sensitive to the use of diesel fuel with a sulfur content of more than 0.5%, which is especially important for countries South America, Asia, Africa.
API CH-4 engine oils meet increased requirements and must contain additives that more effectively prevent valve wear and the formation of carbon deposits on the internal surfaces. They can be used as replacements for API CD, API CE, API CF-4 and API CG-4 engine oils in accordance with the engine manufacturer's recommendations.

API Class CG-4- class presented in 1995.
Motor oils of this class are recommended for four-stroke diesel engines of buses, trucks and tractors of mainline and non-mainline types, which are operated under increased loads, as well as high-speed modes. API CG-4 engine oil is suitable for engines that use high-quality fuels with a specific sulfur content of not more than 0.05%, as well as for engines that do not have special requirements for fuel quality (specific sulfur content can reach 0.5% ).
Automotive oils certified in accordance with API CG-4 class should more effectively prevent wear of internal engine parts, formation of carbon deposits on internal surfaces and pistons, oxidation, foaming, and soot formation (these properties are especially needed for modern engines. main buses and tractors).
API CG-4 class was created in connection with the approval in the United States of new requirements and standards for the ecology and toxicity of exhaust gases (1994 revision). Motor oils of this class can be used in engines for which API CD, API CE and API CF-4 classes are recommended. The main drawback limiting the massive use of this class of motor oils, for example, in Eastern Europe and Asia, is the significant dependence of the motor oil resource on the quality of the fuel used.

API class CF-2 (CF-II) - motor oils intended for use in two-stroke diesel engines, which are operated in difficult conditions.
The class was introduced in 1994. Motor oils of this class are usually used in two-stroke diesel engines that operate under high stress conditions. API CF-2 oils must contain additives that provide enhanced performance protection against wear on internal engine parts such as cylinders and rings. In addition, these car oils should prevent the accumulation of deposits on the internal surfaces of the engine (improved cleaning function).
An API CF-2 certified engine oil has improved properties and can be used in place of earlier comparable oils, subject to the manufacturer's recommendation.

API class CF-4 - engine oils for use in four-stroke diesel engines since 1990.
Motor oils of this class can be used in four-stroke diesel engines, the operating conditions of which are associated with high-speed modes. For such conditions, the requirements for the quality of oils exceed the capabilities of the CE class, therefore CF-4 engine oils can be used instead of CE oils (subject to the appropriate recommendations of the engine manufacturer).
API CF-4 motor oils must contain appropriate additives that reduce the waste of the car oil, as well as protect against carbon deposits in the piston group. The main purpose of motor oils of this class is the use in diesel engines of heavy-duty tractors and other vehicles that are used for long journeys on highways.
In addition, these engine oils are sometimes assigned the API CF-4 / S dual grade. In this case, subject to the availability of the appropriate recommendations of the engine manufacturer, these oils can also be used in gasoline engines.

API CF class (CF-2, CF-4) - motor oils for diesel engines with indirect injection. Classes were introduced from 1990 to 1994. A hyphenated number means two- or four-stroke engine.
Class CF describes engine oils recommended for use in diesel engines with indirect injection, as well as other types of diesel engines that run on fuels of various qualities, including those with a high sulfur content (for example, more than 0.5% of the total weight).
CF engine oils contain additives to better prevent piston deposits, wear and corrosion of copper (copper) bearings, which are important for these types of engines, and can be pumped in the usual way as well as with a turbocharger or compressor. Engine oils of this class can be used where the CD quality class is recommended.

CE API class - engine oils for use in diesel engines from 1983 (obsolete class).
Motor oils of this class were intended for use in some heavy-duty turbocharged engines, characterized by significantly increased working compression. The use of such oils was allowed for engines with both low and high shaft speeds.
API CE engine oils have been recommended for low and high speed diesel engines, manufactured since 1983, which have been operated under high load conditions. Subject to the availability of appropriate recommendations of the engine manufacturer, these oils could also be used in engines for which CD class engine oils were recommended.

API class CD-II - motor oils for use in heavy-duty diesel engines with a two-stroke operating cycle (obsolete class).
The class was introduced in 1985 for use in two-stroke diesel engines and is, in fact, an evolutionary development of the previous API CD class. The main purpose of the use of such auto oils was the use in heavy powerful diesel engines, which were installed mainly on agricultural machinery. Motor oils of this class meet all the working standards of the previous CD class, in addition, the requirements for highly effective engine protection against carbon deposits and wear have been significantly increased.

API CD class - motor oils for diesel engines of increased power, which were used in agricultural machinery (obsolete class). The class was introduced in 1955 for normal use in some diesel engines, both naturally aspirated and turbocharged, with increased cylinder compression, where effective protection against soot and wear is essential. Engine oils of this class could be used in cases where the engine manufacturer did not put forward additional requirements for the quality of the fuel (including fuels with a high sulfur content).
API CD auto oils were supposed to provide increased protection against corrosion of bearings and high-temperature carbon deposits in diesel engines compared to previous classes. Engine oils in this class are often referred to as "Caterpillar Series 3" due to their compliance with the Caterpillar Tractor Company Superior Lubricants (Series 3) certification.

API CC class - motor oils for diesel engines that are operated at medium load conditions (obsolete class).
The class was introduced in 1961 for use in some engines, both naturally aspirated and turbocharged, which were characterized by increased compression. Motor oils of this class were recommended for engines that were operated under moderate and high load.
In addition, subject to the availability of the engine manufacturer's recommendations, such oils could be used in some powerful gasoline engines.
Compared to earlier grades, API CC motor oils were required to provide a higher level of protection against high temperature carbon deposits and bearing corrosion in diesel engines, as well as rust, corrosion and low temperature carbon deposits in gasoline engines.

CB API class - motor oils for diesel engines operating with medium load (obsolete class).
The class was approved in 1949 as an evolutionary development of the CA class when using fuels with a high sulfur content without special quality requirements. API CB motor oils were also intended for use in supercharged engines that were operated in light and moderate conditions. This class has often been referred to as "Appendix 1 Engine Oils", thereby emphasizing compliance with the military regulation MIL-L-2104A Appendix 1.

CA API class - motor oils for lightly loaded diesel engines (obsolete class).
Motor oils of this class are intended for use in diesel engines operating in light and moderate modes on high-quality diesel fuel. In accordance with the recommendations of car manufacturers, they can also be used in some gasoline engines that are operated in moderate modes.
The class was widely used in the 40s and 50s of the last century and cannot be used in modern conditions, unless it is provided for by the requirements of the engine manufacturer.
API CA engine oils must have properties that provide protection against carbon deposits on piston rings, as well as against corrosion of bearings in supercharged engines, for which there are no special requirements for the quality of the fuel used.