Oil Filter

Filters are either spin-on canisters or paper cartridges in a housing. They are replaced at every oil change. A bypass valve lets oil flow if the filter is blocked or the oil is very cold. Filters differ in filtering efficiency, capacity and the opening pressure of their bypass valve, so the correct filter for the engine matters.

Oil from the pump flows through the filter medium, which traps particles. An anti-drain-back valve keeps oil in the filter when the engine is off.

Using a low-quality or wrong filter can reduce protection. The oil filter must always be fitted with a new seal and tightened as specified. A filter that is too tight or has a doubled-up old seal can leak oil quickly; always remove the old seal.