The function and function of the oil filter:
In order to reduce the frictional resistance between relative moving parts in the engine and reduce the wear of parts, oil is continuously transported to the friction surfaces of each moving part, forming a lubricating oil film for lubrication. The engine oil itself contains a certain amount of impurities such as gum, water, and additives. Moreover, during the operation of the engine, the mixture of metal debris and impurities in the air can contaminate the engine oil. Therefore, if the engine oil does not pass through the oil filter and enters the oil circuit directly, the impurities in the engine oil will be carried to the friction surface of the moving parts, accelerating the wear of various components.

Types of oil filters:
There are generally three levels of oil filters, namely oil collection filter, oil coarse filter, and oil fine filter.
1. The collection filter is installed in the front oil pan of the oil pump. In order to prevent large mechanical impurities from entering the oil pump, a metal filter is generally used.
2. The crude oil filter is used to filter out impurities with larger particles in the engine oil. Due to its low resistance to oil flow, it is generally connected in series between the oil pump and the main oil passage, belonging to a full flow filter. Currently, most paper filter cartridges are used as coarse filters.
3. The oil fine filter is installed in parallel with the main oil passage after the oil pump, and there are mainly two types: microporous filter paper type and rotor type. The rotary oil fine filter adopts centrifugal filtration without a filter element, effectively solving the contradiction between the oil's passability and filtration efficiency.
The oil filter, which is equally important as the air conditioning filter, fuel filter, and air filter, is crucial for the engine. The oil filter has a great contribution to extending the engine's lifespan and protecting the engine. So car owners must take good care of the oil filter.