Oil filter consists of filter paper, sealing ring and various valves:
　　A. Filter paper: oil filter has higher requirements on filter paper than air filter, mainly because the temperature of oil varies from 0 to 300 degrees, and the concentration of oil changes correspondingly under drastic temperature changes, which will affect the filtration flow of oil. The filter paper of high quality oil filter should be able to filter impurities under drastic temperature changes while ensuring adequate flow rate. B. Rubber seal ring: the filter seal ring of high-quality oil is made of special rubber to ensure 100% oil leakage. C. Backflow suppression valve: when the engine is turned off, it can prevent the oil filter from becoming dry; When the engine is reignited, it immediately creates pressure to lubricate the engine with oil.
　　D. Overflow valve: when the external temperature drops to a specific value or when the oil filter exceeds the normal service life limit, the overflow valve will open under special pressure to allow the unfiltered oil to flow directly into the engine, which is the key to protect the engine in an emergency.
　　In the cleaning process, the oil filter will inevitably damage the filter paper, seal ring and other parts, greatly reduce the efficiency of the oil filter, so as to cause damage to the engine. Therefore, it is not recommended to reuse the oil filter.