Possible causes:
-
The PCV system is not working properly.
The Fix: Replace PCV valve. -
The engine may have mechanical problems.
The Fix: Check compression to determine engine condition. -
The engine's piston rings may be worn.
The Fix: Replace piston rings. (Generally not a DIY job) -
The engine's valve seals may be worn.
The Fix: Replace valve seals. (Generally not a DIY job)

