Principle of oil filter:
1. During the working process of the engine, metal wear debris, dust, oxidized and colloidal deposits 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 carbon-deposited lubricating oil clean, and to extend its service life. The oil filter should have strong filtering capacity, low circulation resistance, and long service life;
2. The general lubrication system is equipped with several filters with different filtering capabilities, filter collectors, coarse filters and fine filters, respectively connected in parallel or in series in the main oil passage and connected in series with the main oil passage, called full-flow filters. When the engine is working, the lubricating oil is all filtered by the filter, and the parallel filter is called the split filter. The coarse filter is connected in series in the main oil passage, which is a full flow type, and the fine filter is connected in parallel in the main oil passage, which is a split flow type. ；
3. Modern automobile 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.

How to replace the oil filter:
1. Drain the oil in the oil pan first, and use a special wrench to unscrew the oil filter;
2. After the oil is drained, apply new oil to the gasket of the new oil filter;
3. Tighten the oil filter and add new oil to the engine at the position of the engine valve cover;
4. Wait for a while and check whether the oil level is between the lowest and highest marks of the oil gauge.