If the oil filter is not replaced, it will have a great impact. Gasoline is not pure. There are a lot of impurities in it. There are also impurities when the fuel tank cover is opened when refueling or maintenance. The filter inside the fuel tank can only filter large impurities and cannot do anything for smaller particles. 

Oil filter, also known as oil grid. It is used to remove impurities such as dust, metal particles, carbon deposits and soot particles in the engine oil to protect the engine. The oil filter is 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 passage, so it can filter all the lubricating oil that enters the main oil passage.

The split-flow cleaner is connected in parallel with the main oil passage to filter only part of the lubricating oil sent by the oil pump. During the working process of the engine, metal wear debris, dust, carbon deposits and colloidal deposits oxidized at high temperature, water, etc. are constantly mixed into the lubricating oil. The function of the oil filter is to filter out these mechanical impurities and gums, to keep the lubricating oil clean, and to extend its service life.

The oil filter should have strong filtering capacity, low flow resistance, and long service life. Generally, several filters with different filtering capacity are installed in the lubrication system-filter collector, coarse filter and fine filter, which are connected in parallel or in series in the main oil passage respectively. (The one connected in series with the main oil passage is called a full-flow filter. When the engine is working, all lubricating oil is filtered by the filter; the one connected in parallel with it is called a split-flow filter).

Among them, the coarse filter one is connected in series in the main oil passage, which is a full flow type; the fine filter is connected in parallel in the main oil passage, which is a split flow type. Modern car engines generally only have a filter and a full-flow oil filter. The coarse filter filters out impurities with a particle size of 0.05mm or more in the oil, and the fine filter is used to filter out fine impurities with a particle size of 0.001mm or more.