What Are the Five Major Functions of Engine Oil?

[MacDonovan]

Here are the five major functions of engine oil: Lubrication: There is rapid relative sliding between the piston and cylinder, as well as between the main shaft and bearing bush. To prevent excessive wear of parts, an oil film needs to be established between the two sliding surfaces. Auxiliary Cooling: Due to its relatively low specific heat value and its location inside the engine, engine oil itself does not have a cooling function. However, during engine operation, the heat energy generated by fuel combustion can be carried back to the oil tank by the engine oil and then dissipated into the air, assisting the radiator in cooling the engine. Cleaning: Engine oil can carry carbon deposits, sludge, and worn metal particles from engine parts back to the oil tank through circulation. The flow of lubricating oil helps to wash away contaminants generated on the working surfaces of the parts. Sealing and Leak Prevention: Engine oil can form a sealing ring between the piston rings and the piston, reducing gas leakage and preventing the entry of external pollutants. Rust and Corrosion Prevention: Lubricating oil can adhere to the surfaces of parts, preventing contact with water, air, acidic substances, and harmful gases.

[McLeilani]

I've been driving for over twenty years, and engine oil is truly a reliable companion. I particularly value its five major functions. The first major function is lubrication—engine oil coats the internal gears and pistons of the engine, reducing friction between metal parts to prevent excessive wear and extend engine life. The second is cooling—as the oil flows, it absorbs heat and dissipates it, preventing overheating and potential failures, so I don’t worry about engine seizure even on long trips. The third is cleaning—it washes away combustion residues like carbon deposits and impurities, keeping the engine internals clean and maintaining strong performance. The fourth is sealing—oil fills the tiny gaps between piston rings and cylinders, maintaining compression efficiency and improving fuel economy. The fifth is rust prevention—it protects metal components from corrosion, keeping the car like new even after years of use. I change the oil regularly and service the car every 5,000 kilometers, which saves me a lot of money.