According to the filtering principle, oil filters can be divided into three categories: mechanical separation, centrifugal separation and magnetic adsorption. The function of the oil filter is to filter the harmful impurities in the oil from the oil pan, supply clean oil to the crankshaft, connecting rod, camshaft, piston ring and other moving pairs, play the role of lubrication, cooling and cleaning, and extend the service life of the parts.

The oil filter is one of the four filters, and the other three are air filter, air conditioning filter and fuel filter.
1. The common mechanical separation is mesh filtration. There are small holes of a certain size on the surface of the filter material. Solid particles in the oil whose size is larger than the small holes are blocked on the outer surface of the filter material.
2. Centrifugal separation is to make the oil pass through a high-speed rotating rotor, and the impurities are thrown to the inner wall of the rotor by centrifugal force, thus separating from the oil.
3. Magnetic adsorption is the use of permanent magnets to absorb iron particles in the engine oil, so as to prevent them from circulating back and forth in the engine oil, endangering the machine parts.

It is generally recommended to replace the oil filter after 5000km, which can be determined according to the actual driving conditions. Different models of oil filter are different for different models, and the matching efficiency is higher. Besides, it can also protect the engine from the invasion of oil impurities and reduce the damage caused by rapid wear of the engine.