At present, most oil filters are disposable paper and cannot be cleaned. Due to its low cost, good effect, easy maintenance and replacement, it is widely used.
The iron one has a filter type, and the lower part is soaked in engine oil. When the air circulates, the engine oil sticks to the filter and absorbs dust to achieve the purpose of filtration.
There are also centrifugal filters that rotate at high speed to throw impurities onto the inner wall of the rotor.
The latter two can be cleaned and used repeatedly. There are currently very few practical applications.