Viscosity of engine oil for summer, winter. Temperature table.

Engine oil, as you know, performs a very important function in the engine - it lubricates mating parts, ensures the tightness of the cylinders and removes all combustion products. All motor oils are produced by distillation of oil and separation of heavy fractions from it, and a given set of performance characteristics is set through the use of various additives.

One of the most important properties of any engine oil is its viscosity. The viscosity of an oil is the ability to maintain the desired properties in a given temperature range, that is, to remain between mating parts while maintaining fluidity. The temperature range depends on the type of engine and on the climatic conditions in which it is operated. For example, for countries with a warm climate, an oil with a high viscosity index is needed, respectively, it will be thicker than those oils that are used in cold regions.

How to determine the viscosity of an oil?

If you have ever seen plastic oil cans that are sold at gas stations and even in many supermarkets, then they all have type designations - 10W-40, 5W-30, 15W-40, and on cans for gear oils, nigrol , gearbox oils are designated - 80W-90, 75W-80, etc. What do these numbers and letters mean?

W - this is from the word winter - winter, that is, all types of motor oils that have such a designation are suitable for use in winter conditions. True, it must be clarified that winters are different - in the Crimea or in Sochi, temperatures rarely fall to those extreme values ​​\uXNUMXb\uXNUMXbthat happen in Novosibirsk or Yakutsk.

Let's take the most common type in our climatic conditions - 10W-40. The number ten indicates that the viscosity of the oil at a frost of minus 25 degrees (to get this figure, you need to subtract 35 from ten) reaches its maximum value when it is still possible to safely start the engine.

There is also a pumpability index, which determines the lowest air temperature at which the pump will still be able to pump oil into the system. To find out this temperature, you need to subtract forty from the first digit - for 10W-40 we get a value of minus 30 degrees. Thus, this type of oil is suitable for those countries where it is never colder than 25-30 degrees below zero.

If we talk about the second digit in the marking - 40 - then it determines the kinematic and dynamic viscosity at +100 and +150 degrees, respectively. The density of the oil is the greater, the greater this indicator. Oil 10W-40, however, like everything else, in the designation of which the letter W is present, is all-weather and is used at average temperatures from -30 to +40. For those engines that have worked out half their life, it is recommended to use oils where the viscosity index at high temperatures is 50 - 10W-50 or 20W-50.

Viscosity table.

If we talk about gear oils, then there is a special designation scale, which we will not touch on, we will only say that the lower the first digit in the marking, the lower temperatures the oil can retain its properties. For example, 75W-80 or 75W-90 can be used at temperatures from -40 to +35, and 85W-90 - from -15 to +40.

How to choose oil by viscosity?

When choosing engine oil for a particular model, you need to pay attention to a number of designations: engine type, vehicle type, viscosity - diesel / gasoline, injector / carburetor, passenger / truck, and so on. All this is usually indicated on the label. In addition, there are oils recommended by the manufacturer, do not neglect these guidelines, since the engine is designed for a certain level of viscosity.

Since Russia has a very large seasonal temperature difference, you need to choose exactly those oils that are suitable for your climatic conditions. For example, at low temperatures, even if not very extreme, it will be easier to start the engine if 5W-30 oil is filled in, since it retains its performance properties at temperatures down to -40.

If the average annual temperatures are in the range from -20 to +20, then you don’t need to come up with something special and use multigrade oil 10W-40, 15W-40, well, or 10W-50, 20W-50 for “tired” engines.

Tests of some motor oils and their performance.

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