The oil filter is located in the engine lubrication system. Its upstream is the oil pump, and its downstream is the parts of the engine that need lubrication. Its function is to filter the harmful impurities in the engine oil from the oil pan, and provide clean engine oil to the crankshaft, connecting rod, camshaft, supercharger, piston ring and other motion pairs to lubricate, cool and clean, thus extending the life of these parts.

Oil filter structure
According to the structure, the oil filter can be divided into replaceable type, spin on type and centrifugal type; According to the arrangement in the system, it can be divided into full flow type and split flow type. The filter materials used for the oil filter include filter paper, felt, metal mesh, non-woven cloth, etc.
Due to the high viscosity of the engine oil and the high content of impurities in the engine oil, in order to improve the filtering efficiency, the engine oil filter generally has three levels, namely, the engine oil filter, the primary engine oil filter and the secondary engine oil filter. The filter collector is installed in the front oil pan of the oil pump and is generally of metal screen type. The primary oil filter is installed behind the oil pump and connected in series with the main oil duct. It mainly includes metal scraper type, saw dust filter type and microporous filter paper type. Now, microporous filter paper type is mainly used.