Oil viscosity must not be okay
The viscosity of the suitable oil is the primary condition for establishing the oil film on the friction surface. In order to prevent the contact area between the parts, the lubricating oil must have sufficient viscosity to ensure that the oil film can be formed in the moving parts under various operating temperatures. However, the viscosity of the oil is not as large as possible. On the contrary, if the viscosity of the oil is chosen to be too large or too small, it will cause a certain degree of adverse effect on the car.
Viscosity is selected
1. Engine low temperature start-up difficulty
The engine lubrication viscosity is too large, the flow is slow, the oil pressure is high, but the lubricating oil throughput is not much, especially when the low temperature is started, the oil can not be replenished to the friction surface in time, and the temporary dry friction or semi-fluid is most likely to occur at this time. Friction increases the wear of the parts.
2. The effective power of the engine is reduced
Due to the large viscosity of the lubricating oil, the frictional resistance of the friction surface of the machine increases. The friction area of the internal friction mechanism of an automobile engine is large, generally more than 1 square meter. These surfaces are covered with a layer of lubricating oil. When the moving speed of the parts is fast, even if the viscosity of the oil is slightly increased, the loss of friction power will increase a lot. To overcome the increased friction, it is necessary to increase the friction. Consume fuel. On the other hand, the viscosity of the oil is large, and the resistance of the crankshaft during high-speed operation of the crankshaft is also increased, so that the loss of power inside the engine is increased, which lowers the effective power of the engine.
3. The cooling effect is poor
The greater the viscosity of the oil, the poorer the fluidity, the slower the cycle speed, and the slower the heat removal from the friction surface, so the cooling effect is poor and the engine is easily overheated.
4. Poor cleaning effect
The viscosity of the oil is large, the circulation speed of the oil is slow, and the number of passes through the filter is also reduced. The worn metal chips, carbon particles, dust and other impurities cannot be taken away from the friction surface in time, and the cleaning effect is poor.
Viscosity is chosen small
1. Oil film is easily destroyed
The viscosity of the oil is small. On the high-temperature friction surface, it is difficult to form an oil film of sufficient thickness. The oil film has poor bearing capacity and is easily damaged under load, so that the machine parts are not properly lubricated and the wear is increased.
2. The sealing effect is not good
The viscosity of the oil is small, the sealing effect is poor, and the cylinder is prone to air leakage, which not only causes the power to drop, but also easily causes the exhaust gas to enter the crankcase, so that the oil is diluted and contaminated.
3. Increase oil consumption
The viscosity of the oil is small, the sealing property is not good, and the evaporation loss is large. This makes it easy for the oil on the cylinder wall to enter the combustion chamber, causing the oil to burn, which not only increases the consumption of the oil but also causes the combustion to be incomplete, and the carbon deposit in the combustion chamber increases.
It can be seen that the engine oil viscosity is too large or too small is not good, the correct choice of oil viscosity is king.