First, a little theory. The key task of automasels is to prevent dry friction of moving parts inside the motor, which can lead to a decrease in its motor life. Also, oil lubrication plays the role of a sealant in the cylinders. In the old days, motor oils were divided into summer and winter. However, now the properties of a good engine oil should be such that it provides a cold start of the engine in the bitter cold and remains viscous in the hot summer heat.

Motor oils are divided into several categories:

  • mineral — made directly from petroleum products; such oils have the most delicious price tag, however, the period of preservation of the useful properties of the substance during operation is at a low level;
  • synthetic — obtained by chemical synthesis in laboratories; "synthetics" is designed for operation in a wide temperature range and does not lose its working properties when the engine is heated or cooled;
  • semi—synthetic — a kind of golden mean — a natural base with the addition of artificially created compounds.
A clear difference between the structure of mineral and synthetic motor oils.

The oil base is generously "seasoned" on top with a package of additives that perform tasks of a different nature — from stabilizing the viscosity at certain temperatures to cleaning the internal parts of the engine. For example, the thickness of the oil film depends on the additives. If it turns out to be more than the gaps allowed by the motor manufacturer, the piston group will constantly overheat, if less, the oil will burn out beyond the norm. Therefore, a separate group of motor oils, indicated in the tolerances of the automaker, is suitable for a specific engine. But more on this below, and first let's talk about the viscosity of the oil.

Motor oils for passenger cars

Viscosity

Taking into account the properties of the oil to thicken at low temperatures and liquefy when heated, the American Association of Automotive Engineers SAE has developed a classification of auto oils by viscosity level, divided into summer and winter lubricants. And since the ball is now ruled by so-called all-season oils, two numbers that determine the viscosity appear in the designation of modern auto oils (for example, SAE 5W-30 or SAE 15W-60).

Winter viscosity classes include SAE 0W, 5W, 10W, 15W, 20W and 25W, and summer — SAE 20, 30, 40, 50 and 60. The higher the number in the summer category, the better the oil retains its viscosity under prolonged exposure to high temperatures. And vice versa — the lower the W index, the better the oil tolerates frosts, without thickening beyond the prescribed norm.

The generally accepted classification of the viscosity of motor oils according to SAE with reference to the outdoor temperature.

When selecting oil according to the viscosity level, take into account the main rule: the manufacturer has already taken into account all the necessary driving modes and recommended exactly those viscosity parameters that are most suitable for this engine.

Important! Only those products that are recommended by the car manufacturer should be poured into the engine. Information about them is usually contained in the service book or the operating instructions of the machine.

Let's consider the situation from a practical point of view. Let's assume that the car manufacturer recommends pouring 5W-30 oil into the engine on a year-round basis. It completely retains its properties at outdoor temperatures from -25 °C to +30 °C. The reason for the seasonal oil change is a constant deviation of the air temperature from the oil specified in the characteristics by more than 10 °C. That is, in a frosty climate, you can safely switch to 0W-30 oil, which remains fluid and is well pumped through the system even in a strong "minus", and at a summer norm of +35 °C overboard, the engine oil can be changed to 5W-40. Otherwise, the viscosity and the created protective film may not be enough.

Another factor for switching to a different oil is the degree of engine wear. Over time, its requirements for the density of the lubricating fluid change, as a result, it is recommended to use an oil with a higher index of high-temperature viscosity. Too liquid oil for worn—out engines is not the best choice, because due to the increased gaps, the lubricating film will simply drain from the parts. To compensate for these gaps, engines with a mileage of more than 150K km need to be "soldered" with more viscous products.

Semi-synthetic motor oils

The next important point of the programme:

Tolerances

Any canister with oil must necessarily be marked to ensure that the car oil has passed internal certification from the vehicle manufacturer and is authorized by it for use in engines. The lubricant perfect for one engine may turn out to be disastrous for another — some oil parameters for different engines are mutually exclusive. This, for example, is the thickness of the oil film discussed above, which the "slurry" forms on the "insides" of the engine — the most important of the characteristics of car oil.

Tolerances are needed because the production technologies of motors vary from manufacturer to manufacturer. Accordingly, the materials for manufacturing the internal parts of the engine differ. This is where all kinds of additives that are contained in the oil come into the arena, and the issues of their interaction with these very materials.

Important! The admission must be viewed in the technical documentation for the car. It must be followed unquestioningly.

Each automaker has its own marking of engine oil tolerances.

The tolerances on the oil canister are usually presented in this form.

The VAG Concern permits the use of certified oil marked with VW symbols indicating a digital code combination for a specific power unit. In Mercedes cars, you can pour oils that have received MB approval in conjunction with a combination of numbers for a specific motor. Opel engines are allowed to pour car oils that have received GM-LL-A-025 or GM-LL-B-025 certificates, etc.

What kind of oil can be added to the engine?

During the operation of a car, for various reasons, there may be a decrease in the level of lubrication, so this tricky question excites the minds of many motorists. The answer to it is simple: the best option for topping up is considered to be mixing oils from the same manufacturer that have the same base (mineral, synthetic or semi-synthetic, respectively). But it is highly discouraged to breed a cocktail with various types of lubricants in the engine for the reasons that each product has a unique package of chemical additives.

Useful advice! In order to assess the level of lubrication in the engine as accurately as possible, it is recommended to take measurements after the engine is fully warmed up, after waiting 10-15 minutes for a pause. During this period, the oil has time to drain back into the pan, and the readings on the probe allow you to make an objective assessment.

If you are aware that the engine of the "iron horse" has the property of "eating up" the lubricant, take the car oil with a reserve — instead of a 4-liter canister, buy a liter more. So you will save yourself from possible problems with finding oil on the way and protect the power unit of the car from "eating" the wrong lubricants.

Not a nail for you, not a rod on the roads!

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