The working principle of oil filters is generally divided into three types according to impurity filtration methods: mechanical separation, centrifugal separation, and magnetic adsorption.

Mechanical separation of oil filter
According to their functional forms, they can be divided into three types: pure mechanical separation, overhead separation, and adsorption separation.

The common method of pure mechanical separation is filter filtration, which uses a certain aperture filter material to filter mechanical impurities and oil sludge. Impurities with a particle size larger than the filter hole are blocked by the filter material and filtered out.
Aerial separation refers to the phenomenon where n small particles attach to the inner wall of the filter hole, gradually increasing in number, causing the filter hole to gradually become smaller and forming an aerial phenomenon, resulting in the filtered particle size being smaller than the filter hole size. Due to the irregular shape of most particles in engine oil, aerial phenomena are prone to form. In addition, adhesive substances in engine oil often adhere to the surface of the filter material or the inner wall of the filter hole to form adsorption.
The actual filtering situation of oil filters is generally not a single principle, but may be a combination of the above.

Oil filter centrifugal separation
The oil passes through a high-speed rotating rotor, causing impurities in the oil to be thrown towards the inner wall of the rotor by centrifugal force, thus separating from the oil.

Oil filter magnetic adsorption
By utilizing the magnetic force of a permanent magnet, iron particles in the oil are adsorbed, preventing them from circulating back and forth in the oil lubrication system, endangering engine components and achieving filter filtration effect.