Its working principle is that during the operation of the automobile engine, the metal debris and dust are oxidized into carbon deposits, water and colloidal deposits under the high temperature environment and constantly mixed into the lubricating oil. At this time, the oil filter can filter these impurities. The function of the oil filter is to keep the lubricating oil clean and prolong the service life of the lubricating oil. The oil filter has the characteristics of small flow resistance, long service life and strong filtering and cleaning ability. Generally, in the lubrication system, it is necessary to install multiple filters with different filtering capabilities, including: coarse filter, fine filter and filter collector, which are respectively connected in series or in parallel in the main oil channel. The full-flow filter is mainly connected in series with the main oil passage. When the engine is working, all the lubricating oil is filtered out through the filter; The shunt filter is connected in parallel with the main oil passage. The primary filter is in series with the main oil passage, while the secondary filter is in parallel with the main oil passage. Now, with the further improvement of automobile technology, only one full-flow oil filter and filter collector are generally installed. The coarse filter mainly filters out impurities with particle size of more than 0.05mm in the oil, while the fine filter can only filter small impurities of about 0.001mm. The mechanical filter can be divided into the following types according to its structure: centrifugal type, replaceable type and spin-on type.