A filter refers to an accessory that filters impurities or gases through filter paper. Generally refers to the car filter, is the engine accessories.
According to different filtering functions, it is divided into: oil filter, fuel filter (gasoline filter, diesel filter, oil-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.