During oil maintenance, the following problems will occur if the oil filter is not changed:
1. The function of the oil filter is to filter out harmful impurities in the oil from the oil pan, and supply clean oil to the crankshaft, connecting rod, camshaft, piston ring and other moving parts to play the role of lubricating, cooling, cleaning, and extending the life of parts;
2. After a long time use of the filter, its filtering efficiency will decrease, and the pressure of the oil passing through the filter will be greatly reduced. When the oil pressure drops to a certain level, the filter bypass valve will open, and the unfiltered oil will enter the oil circuit through the bypass. Impurities will increase the wear of the machine parts. In severe cases, it will even block the oil passage and cause mechanical failure. Therefore, the oil filter must be replaced regularly;
3. If the filter is not replaced for a long time, the filter will be clogged due to dirt deposits, and pollutants will directly enter the engine, which will aggravate the wear of the parts. Only replace the engine oil without changing the engine filter, the pollutants in the old engine filter will re-enter the fresh engine oil to circulate, making the oil change meaningless;
4. Engine oil lubricates the engine. A very important role is to take away the dirty things inside the engine, and these dirty things mainly need oil filtration to filter. If the oil is changed without changing the oil filter, the dirt cannot be completely removed, and the replaced oil will lose its performance in terms of cleaning.