Here is the ultimate answer to the role of engine oil

Engine oil is engine oil. It can play the role of lubrication and antifriction, auxiliary cooling, sealing, anti leakage, anti rust and anti-corrosion, shock absorption and buffering. Known as the "blood" of the car.
The engine is the heart of the car. There are many metal surfaces in the engine that move against each other. These parts move fast and the environment is poor. The working temperature can reach 400 ° C to 600 ° C. Under such bad working conditions, only qualified lubricating oil can reduce the wear of engine parts and prolong the service life. What requirements should qualified lubricating oil meet? In other words, what are the seven functions of lubricants?
1. Lubrication: there is fast relative sliding between piston and cylinder, and between spindle and bearing bush. To prevent parts from wearing too fast, oil film should be established between two sliding surfaces. There is enough thickness of oil film to separate the sliding part surface, so as to achieve the purpose of reducing wear.
2. Auxiliary cooling: the engine oil has no cooling effect because of its low specific heat value and inside the engine. However, heat energy is generated by fuel combustion in the engine. When the engine is working, the oil can bring the heat back to the oil tank and then dissipate it into the air to help the water tank cool the engine. The real cooling effect is the water (or antifreeze liquid) outside the engine shell.
3. Clean and disperse: good engine oil can bring carbide, oil sludge and wear metal particles on engine parts back to the oil tank through circulation. Through the flow of lubricating oil, it can wash the dirt on the working face of parts and play the role of cleaning the engine.
4. Sealing and leak proof: oil can form a sealing ring between piston ring and piston to reduce gas leakage and prevent external pollutants from entering.
5. Anti rust and anti-corrosion: lubricating oil can be absorbed on the surface of parts to prevent water, air, acid substances and harmful gases from contacting with parts.
7. Anti wear: adding lubricant to the friction surface can reduce the friction coefficient, thus reducing the friction resistance, saving energy consumption and reducing wear; Lubricant can reduce the friction loss caused by abrasive wear, surface fatigue and adhesive wear.