Any liquid has a viscosity, it is thisthe characteristic determines its fluidity. Automobile oil is designed to perform a number of tasks, so each parameter has its effect on quality in general. The viscosity of the oil is no exception.
The main technical task of any motoroil - to stop the friction of moving parts while the engine is running. Ideally, the frictional force should be minimal with high oil life, its properties should remain constant over a wide range of temperatures.
Implement this idea in practice and createa substance that would meet all the requirements is very difficult. In addition, it must be taken into account that during the movement the load is constantly changing, and the temperature of the motor oil in the engine will be very different, in some moments it will reach 140-150 degrees.
Nevertheless, specialists are constantly working onthe creation of motor oil, which would be as close to its properties as possible to the necessary parameters. Science has made a broad step forward in this direction, so modern engines are much more powerful and efficient than their predecessors, and they work longer.
The viscosity of oil is one of the most importantparameters. While the engine is cold or does not work at full strength, the oil in the engine begins to gradually thicken. In this regard, there is a requirement that the oil should remain liquid under any circumstances, even if the temperature on the street is well below zero. The better the fluidity, the better it will protect the engine during operation.
Oil viscosity index
To determine the viscosity of oil, specialistsintroduced a special index, which reflects the dependence of the change in the main parameters (including viscosity) on temperature. The higher the index, the better the oil maintains its fluidity even at low temperatures.
The oil must, under all circumstances, remainon engine parts, but at the same time maintain its fluidity. Classification of the oil is usually produced by the index, as this is one of the most important indicators, which to some extent reflects the main characteristics.
The 5W index means that the engine can berun even at a temperature of -35 degrees without preheating. The lower the temperature, the thicker the oil becomes, which makes it difficult for the engine to "rotate", which means that the starter can no longer turn the engine. When choosing a specific car oil, you always need to focus on the main tasks, but do not forget at the same time about the recommendations of the car manufacturer. It is necessary to take into account the design of the engine, the degree of wear, the most frequent operating modes and so on.
Among other things, the viscosity of the oil affectsthe efficiency of the engine, namely the distribution of energy. When the engine is running, some of the energy is expended on its own internal needs, i.e. this means that the engine needs energy to overcome the frictional force that occurs when different parts come into contact. The better and more efficient the oil, the less energy will be spent on it.
Now the classification of oils is used,introduced by the American Society of Automotive Engineers. To get one or another category, the oil must meet certain requirements. The kinematic viscosity of the oil is determined at temperatures of 40 and 100 degrees, and is measured when passing a special curved tube - a viscometer. On the basis of this, the real viscosity of the oil is determined, for the detection of which a special formula is applied. Such tests can determine the quality of the oil, as well as assign a certain category.