Oil level too low
- Oil consumption
- External oil leak
- Worn piston ring
- Improperly installed piston rings
- Worn cylinders
- Worn stem seals
- Worn valve guide
Low oil pressure
- Oil level low
- Clogged oil strainer
- Faulty oil pump
- Internal oil leak
- Incorrect oil being used
- Pressure relief valve stuck open
- Clogged oil filter screen
No oil pressure
- Oil level low
- Clogged oil strainer
- Broken oil pump drive chain
- Broken oil pump drive and/or driven sprocket
- Damaged oil pump
- Internal oil leak
High oil pressure
- Pressure relief valve stuck closed
- Clogged oil gallery or metering orifice
- Incorrect oil being used
Oil contamination
- Oil or filter not changed often enough
- Worn piston ring
Oil emulsification
- Blown cylinder head gasket
- Leaky coolant passage
- Entry of water