What is the problem that air filters often have oil?

Check whether the air filter is blocked or wet. If the air filter is blocked, the intake resistance of the engine will be too large, and there will be oil backflow in the intake port of the engine.

If the car is equipped with a supercharger, it is necessary to check the working condition of the supercharger. If the seal of supercharger fails, there will be oil leakage, and the air filter will also have oil.

Poor sealing of the valve oil seal will also cause oil leakage at the air inlet, and the air filter will also have oil, which needs to be measured by checking the oil consumption. If the amount of oil (mileage or oil change interval) added during the oil change cycle is too large, it is necessary to check the valve.

You need to check the amount of oil in the oil pan. If you add too much oil, the pressure in the crankcase will be too high, and there will be oil in the air intake and even the air filter. Just put away the excess oil and add it to the standard range.