Oil filter, also known as oil filter. It is used to remove impurities such as dust, metal particles, carbon sediments and soot particles in the oil to protect the engine. Oil filters are divided into full-flow type and split-flow type. The full-flow filter is connected in series between the oil pump and the main oil channel, so it can filter all the lubricating oil entering the main oil channel. The split-flow filter is connected in parallel with the main oil channel and only filters part of the lubricating oil sent by the oil pump.