Now, when many car owners choose lubricating oil for their car, they still stubbornly believe that the higher the viscosity, the better, and choose high-viscosity oil as much as possible. Is that really the case? In fact, this statement is wrong: the viscosity of lubricating oil is not only the basis for the classification of lubricating oil, but also is related to the power of the engine, the degree of wear of the moving parts, the degree of sealing of the piston rings, the lightness of the cold start of the engine, and the temperature is closely related.
If the oil viscosity is too high: 1. Difficulty starting the engine at low temperature The viscosity of the oil is too large, the pumping performance of the oil is poor, and the oiling is too slow when the engine is started at a low temperature. At this time, temporary dry friction or semi-fluid friction is most likely to occur, which is the main reason for engine wear.
2. Large power loss The viscosity of the oil is large, the frictional resistance of the friction surface of the parts increases, and the frictional power loss also increases. On the other hand, the resistance of the crankshaft to stir the oil will also increase, resulting in an increase in the loss of power inside the engine.
3. Poor cleaning and cooling The oil viscosity is high, the fluidity is poor, the circulation speed is slow, the speed of removing heat from the friction surface is slow, and the cooling effect is poor. The circulation speed of the oil is slow, and the number of times passing through the filter is also less, and the worn metal chips, carbon particles, dust and other impurities cannot be taken away from the friction surface in time, which may easily cause the engine to heat up.
If the lubricating oil viscosity is too low: 1. The oil film is easily damaged The viscosity of lubricating oil is small, it is not easy to form a thick enough oil film, the bearing capacity of the oil film is poor, and it is easy to be damaged under the load, so that the parts cannot be lubricated normally, which will increase the wear.
2. Poor sealing The viscosity of the lubricating oil is small, the sealing performance will be poor, and the cylinder will easily leak, which will not only reduce the power, but also easily cause the exhaust gas to escape into the crankcase, diluting and polluting the lubricating oil.
3. Increase the consumption of lubricating oil The viscosity of the lubricating oil is small, the sealing performance is not good, and the evaporation is large, so that the oil on the cylinder wall can easily enter the combustion chamber, causing oil burning, which not only increases the consumption of lubricating oil, but also causes incomplete combustion and combustion chamber accumulation. Carbon increases, the exhaust emits black or blue smoke, and engine power decreases. It can be seen that it is not good for the viscosity of engine lubricating oil to be too large or too small. It must be selected appropriately. This "appropriate viscosity" means that a thick enough oil film can be formed on the friction surface of the parts to ensure the normal operation of the parts.
