What is the function of engine lubricant?

[Jamie]

Engine lubricant serves the following purposes: reducing friction between moving parts of the engine, ensuring smooth engine operation, improving mechanical efficiency, cleaning the engine and removing residual impurities in the filter. Engine lubricant is required wherever there is relative motion between metal components in the engine. If the engine is not protected by lubricant during operation, dry friction will occur in tightly fitted areas such as between the piston and cylinder wall, or between the connecting rod bearing and crankshaft. The heat generated in a short period of time can be sufficient to melt the metal, causing damage to components or even seizure (such as piston scuffing or crankshaft bearing seizure), leading to engine failure. Therefore, in daily use, engine lubricant must be regularly inspected, replenished or replaced.