There is a lot of oil in the intake pipe of Ford Mondeo. What happened?

The engine intake manifold of Mondeo 1.5T has engine oil, which will appear in many cars, some of which are rare, for the following reasons;

1. Oil evaporates and passes through the oil-gas separator. When there is no problem with the oil-gas separator, a small amount of oil will run into the gas pipe, which is a small amount of oil.

2. When there is a problem with the oil-gas separator, a large amount of oil and gas will enter the intake pipe, which is abnormal and needs to be replaced.