The function of the oil filter is to filter out harmful impurities in the oil from the oil pan, and then supply the crankshaft, connecting rod, camshaft, supercharger, piston ring and other moving parts with clean oil to lubricate, cool and clean, thus prolonging the life of these parts. According to the structure, the machine 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 and split flow.

Oil filter plus magnet function:
1. First of all, the iron shell on the outside of the filter element will shield a considerable part of the magnetic flux, which greatly reduces its internal magnetic properties. When the oil passes through the filter, the large iron filings have been filtered, while the small ones are filtered by the filter paper and cannot enter the oil passage;
2. Also, when the oil pump is working, the oil flows rapidly at a high pressure. If there is iron filings in the oil, it is difficult to be absorbed, and even if there is adsorption, it will be washed away;
3. In addition, the oil pan screw is equipped with a magnetic ring. When the vehicle is turned off, the suspended particles in the oil will settle down and be sucked on it, and this position is the bottom dead corner that will not be washed by oil pressure. Furthermore, there is a strong magnet attached to the engine, and its magnetic field may cause interference to peripheral electrical appliances such as vehicle wiring, induction plugs, and computer boards, resulting in malfunctions. Therefore, I think that changing the oil filter regularly and on time is more effective than other measures.