The oil filter, also known as the oil grid, is located in the engine lubrication system. The upstream of the filter is the oil pump, and the downstream is the parts that need to be lubricated in the engine. Oil filters are divided into full flow and split flow. The full-flow filter is connected in series between the oil pump and the main oil passage, so it can filter all the lubricating oil entering the main oil passage. The diverter filter is connected in parallel with the main oil passage to filter only part of the lubricating oil sent by the oil pump.

The role of the oil filter
The oil filter filters out harmful impurities in the oil from the oil pan, and supplies the crankshaft, connecting rod, camshaft, supercharger, piston ring and other moving parts with clean oil, which plays the role of lubrication, cooling and cleaning, thereby prolonging the life of these parts. Simply put, the function of the oil filter is to filter the oil, make the oil entering the engine cleaner, and prevent impurities from entering the engine and damaging the precision components.

Oil filter structure
According to the structure, the oil 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 type and split-flow type. The filter materials used in oil filtration include filter paper, felt, metal mesh, non-woven fabric, etc.

How the oil filter works
During the working process of the engine, metal wear debris, dust, carbon deposits oxidized at high temperature, colloidal sediment, water, etc., are continuously mixed into the lubricating oil. The function of the oil filter is to filter out these mechanical impurities and gums, keep the lubricating oil clean and prolong its service life. The oil filter should have the characteristics of strong filtering ability, small flow resistance and long service life. In general, several filters with different filtration capacities are installed in the lubrication system—the collector, the coarse filter and the fine filter, which are respectively connected in parallel or in series in the main oil passage. (The one connected in series with the main oil passage is called a full-flow filter. When the engine is working, all the lubricating oil is filtered by the filter; the one connected in parallel with it is called a split-flow filter). Among them, the first filter is connected in series in the main oil passage, which is full flow; the fine filter is connected in parallel in the main oil passage, which is divided flow. Modern car engines generally only have a collector filter and a full-flow oil filter. The coarse filter filters out impurities with a particle size of 0.05mm or more in the oil, and the fine filter is used to filter out fine impurities with a particle size of 0.001mm or more.