Engine oil contamination
During the operation of the car, engine oil is exposed to various kinds of influences. As a result, it is quite difficult to establish the nature of the influence of various operational factors on the operation of the oil. During prolonged operation of the engine with heavy loads and high speeds, the engine oil heats up to a high temperature. Under the influence of high temperature and atmospheric oxygen, the oil oxidizes. Oxidation products thicken the oil and can deposit on piston tops, piston ring grooves and valve stems. This can also lead to coking of the valve discs.
Reducing the viscosity of gasoline engine oil
If the air/fuel mixture contains excess fuel, this results in reduced engine power. If the engine is not warm enough (urban traffic), this is the cause of incomplete combustion of the fuel. Soot, oil deposits and other products, unburned fuel and moisture condensate lead to the formation of slag, acids and asphalt. Unburned fuel settles on the cold walls of the cylinders and flows into the crankcase, while washing off the oil film from the surface of the cylinders and pistons. The consequence of this is a deterioration in the lubrication of the cylinders and a decrease in the viscosity of the oil, which reduces its lubricating properties. If the oil level is too low, a complete oil change is necessary. Since in a busy mode of movement (hot engine) Gasoline evaporates from the oil, it is necessary to check the oil level more often. This is primarily related to the winter period of the car, when the number of cold starts increases.
Engine oil viscosity
Viscosity is the property of the resistance of a liquid to the internal movement of its layers. The viscosity of an oil changes with its temperature. With increasing temperature, the viscosity of the oil decreases, which leads to a decrease in the fabulous properties of the oil film. When the temperature drops, the viscosity of the oil increases, which leads to an increase in friction in the moving parts of the engine.
In a cold engine, the viscosity of the oil must be sufficient to ensure that the engine is started by the starter and to ensure that the oil reaches the friction surfaces. This requires the use of an engine oil that changes its viscosity as little as possible with temperature.
The viscosity of the oil is indicated by the SAE system (Society of Automative Engineers). For example, SAE 30, SAE. 10, etc. The higher the SAE number, the higher the viscosity of the oil. The viscosity of an oil does not give one complete picture of its lubricating properties.