Filters are used in all systems of the car that use liquids. Brake hydraulics, fuel and oil circuit are the most important examples of fluid systems that use filters. In addition, the filters are also needed to clean the intake air. This applies to both internal ventilation and air required for the fuel-air mixture in the engine. In course of time filters wear out. In some case it is possible to clean them, but often they must be replaced.

Car parts makers indicate period of filter changing. Checking of the filter is a part of the technical inspection. Sometimes, dirty or worn filter is the main cause of the power loss. It is not difficult to replace the filters. The biggest challenge is to get to the place of installation. For example, to install the salon air filter is a relatively costly procedure.