A drain plug is a plug that allows liquids to drain from a tank-like an engine oil pan or sump. Dirt can cause corrosion and reduce the engine's lifespan over time. Regular oil and filter changes help the smooth engine function by eliminating particles and sludge. The oil drain plug is a metal or plastic screw stopper. The drain aperture seals by the oil drain stopper with a sealing ring. When changing the oil before refilling, this aperture is required to drain waste oil.