The filter is part of the engine lubrication system and is used to filter impurities from the oil.

Upstream of the filter is the oil pump and downstream is every part of the engine that needs to be lubricated. Therefore, the function of the filter is to filter out the harmful substances in the oil, and transmit the cleaner oil to the supercharger, camshaft, connecting rod, piston ring and crankshaft and other body parts, so as to prolong the life of these auto parts in time. The filter is composed of a stainless steel bracket and an aluminum shell, and a chrysanthemum-shaped high-efficiency filter paper is mounted on the bracket to increase the flow area. It should be noted that since EFI filters are often subjected to fuel pressures of 200 to 300 kPa, carburetor filters cannot be used in common with EFI filters.

According to different filtering functions, it is divided into: oil filter, fuel filter (gasoline filter, diesel filter, fuel water separator, hydraulic filter), air filter, air-conditioning filter, etc. The engine has three filters for air, oil and fuel, generally called "three filters", plus an air conditioner filter, commonly known as four filters. It is responsible for the filtering of the lubrication system, the medium in the combustion system, the engine air intake system and the cabin air circulation system.