Mechanical Causes Of High Oil Consumption

Leaks 

Worn crankshaft and crankshaft seal, external leakage, for example leaking gaskets.

Crankcase ventilation 

Overpressure in the crank case caused by blocked crankcase ventilation.

Pistons and piston rings 

Worn piston ring groove. Worn, scratched, broken or damaged piston rings. Blocked scraper rings. Incorrectly installed piston rings.

Cylinder walls 

Worn or scratched cylinder walls.

Valves 

Worn valve guides or valve stem. Worn, damaged or missing valve stem seals.

Cylinder head 

Internal leakage between the oil ducts and leakage to the combustion chamber.