It is used to remove dust in the engine oil, metal particles. carbon deposits and sooty particles and other impurities so as to protect engine. Usually, oil filter is divided into full flow type and shunt type. The full flow filter is connected between the oil pump and the main oil gallery in series, hence, it can filter all lubricating oil entering the main oil gallery. However, the shunt filter is connected with the main oil gallery in parallel, only can filter part of the lubricating oil.