Classification of oil filters: full flow and split flow. The oil filter is one of the four filters. The other three are the air filter, the air conditioner filter and the fuel filter. The function of the oil filter is to filter the impurities in the oil and protect the engine from wear and tear. .

Full-flow oil filter: The full-flow filter used in modern automobile engines is ly filter type. The oil enters the center of the filter from the periphery of the paper filter element, and then flows into the main oil passage of the body through the oil outlet. When the oil flows through the filter element, impurities are trapped on the filter element.

Split-flow fine oil filter: There are two types of split-flow fine oil filter, filter type and centrifugal type. The filtration type has the contradiction between the filtration capacity and the passing capacity, while the centrifugal type has the advantages of high filtration capacity, large passing capacity, and is not affected by sediment. Therefore, the centrifugal oil filter is often used as a split-flow oil filter for vehicle engines.

The filtering principle of oil filter can be divided into three categories: mechanical separation, centrifugal separation and magnetic adsorption.
1. Grid filtration is commonly used in mechanical separation. There are small holes of a certain size on the surface of the filter material. The solid particles in the oil, those with a size larger than the small holes, are blocked on the outer surface of the filter material.
2. Centrifugal separation is to pass the oil through a high-speed rotating rotor, and the impurities are thrown to the inner wall of the rotor by centrifugal force, thereby being separated from the oil.
3. Magnetic adsorption is the use of permanent magnets to attract iron particles in the oil, so that they are not allowed to circulate back and forth in the oil, which will harm the machine parts.