What is the purpose of engine oil?
2 Answers
The seven main functions of engine oil are lubrication, cooling, cleaning, sealing and leak prevention, rust and corrosion prevention, shock absorption, and anti-wear. Engine oil is the lubricant used in engines, composed of base oil and additives. The specific functions of engine oil are as follows: 1. Lubrication: There is rapid relative sliding between pistons and cylinders, as well as between main shafts and bearing shells. To prevent excessive wear of parts, an oil film needs to be established between the two sliding surfaces. A sufficiently thick oil film separates the surfaces of relatively sliding parts, thereby reducing wear. 2. Auxiliary cooling: Engine oil has a relatively low specific heat value and, being inside the engine, does not inherently 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, helping the radiator cool the engine. The actual cooling is done by the water (or antifreeze liquid) outside the engine casing. 3. Cleaning: Good engine oil can carry carbon deposits, sludge, and worn metal particles from engine parts back to the oil tank through circulation, flushing away dirt generated on the working surfaces of parts via the flow of the lubricating oil. 4. Sealing and leak prevention: Engine oil can form a sealing ring between the piston rings and pistons, reducing gas leakage and preventing external contaminants from entering. 5. Rust and corrosion prevention: Lubricating oil can adhere to the surfaces of parts, preventing contact with water, air, acidic substances, and harmful gases. 6. Shock absorption: When the pressure at the engine cylinder port rises sharply, suddenly increasing the load on the pistons, piston skirts, connecting rods, and crankshaft bearings, this load is transmitted and lubricated through the bearings, cushioning the impact load. 7. Anti-wear: Adding a lubricant to friction surfaces can reduce the friction coefficient, thereby decreasing friction resistance and saving energy consumption. Reducing wear: Lubricants between friction surfaces can reduce wear caused by abrasive wear, surface fatigue, adhesive wear, etc.
I drive to work every day and think engine oil is particularly important. It's like the blood of a car, flowing everywhere inside the engine to lubricate metal parts. Imagine metal surfaces rubbing against each other would generate a lot of heat and wear. With engine oil coating the surfaces, friction is reduced, making the engine run much smoother. Additionally, engine oil has a cleaning function—it carries away carbon deposits and tiny metal particles left from combustion, preventing these from clogging oil passages or scratching components. I usually change the oil every 5,000 kilometers. Timely oil changes maintain cooling efficiency and sealing performance, avoiding engine overheating or oil leaks. Not changing the oil for a long time can cause it to deteriorate and form sludge, potentially leading to premature engine failure, and the repair costs would be terrifying by then.
