1. Lubrication and wear reduction: an oil film is formed on the surfaces of two sliding parts, so that the parts will not rub during operation and the parts will run smoothly.
2. Clean and dispersed: Good engine oil can wash away the dirt on the surface of parts through the flow of engine oil, suck away some tiny metal chips inside the engine, and then scrape off the oil pan by the piston oil ring.
3. Cooling: When the engine is running, high temperature is generated. When the engine oil reaches the running position, it will absorb heat and then take it away to help the parts dissipate heat.
4. Sealing and leak-proof: it means to form a sealing ring between the piston ring and the piston by means of oil film to prevent the burnt exhaust gas from escaping into the crankcase.
5. Anti-rust and anti-corrosion. Good engine oil can adhere to the surface of the parts to prevent air, acidic substances and harmful gases from contacting with the parts, so that the parts are not corroded by the atmosphere and water, and the engine is protected.
6. Shock absorption and buffering: When the pressure at the engine cylinder mouth becomes larger, the load on the piston, piston ring, connecting rod and crankshaft bearing suddenly becomes very large, and this load is lubricated through the bearing, so that the impact load it bears plays a buffering role.