Diesel filter element filters fine impurities in diesel oil, and oil-water separator filters water in diesel oil. Their functions are totally unnecessary. Oil-water separator can only filter water, but not impurities, so both are very important for diesel vehicles.
The diesel filter element needs to be replaced regularly, otherwise it will easily lead to the problem of oil blockage. Generally speaking, it is best to check the diesel filter every 10,000 kilometers. If the road conditions are not good, we should consider replacing them in advance.