Do I need to replace the oil drain plug every time?

[StAugust]

You don't need to replace the oil drain plug every time, just replace the washer of the drain plug. The drain plug is fixed on the oil pan, and its function is to drain the engine oil from the engine. The washer of the plug can provide sealing through compression, and also prevent loosening and falling off caused by vibration. The main functions of engine oil are to reduce friction and wear of moving parts, clean sludge (one of the functions of dispersants) and varnish (cleaners) in the engine, neutralize acids from fuel and lubricant oxidation (cleaners), improve the sealing of piston rings, and cool the engine by carrying away heat from moving parts.