When the engine is burning large amounts of oil, check for the following, as necessary:
The engine oil level may be to high.
The engine oil may be to thin.
Wrong size of piston rings.
Clogged piston ring grooves or oil return slots.
Insufficient tension of the piston rings.
Piston rings may be sticking in the grooves.
Excessively worn piston ring grooves.
Reversed (up-side-down) compression rings.
Non-staggered piston ring gaps.
Improper Positive Crankcase Ventilation (PCV) valve operation.
Damaged valve O-ring seals.
Restricted oil drain back holes.
Worn valve stem or guides.
Damaged valve stem oil deflectors.
Too long intake gasket dowels.
Mismatched rail and expander of the oil ring.
Excessive clearance of the main and connecting rods.
Scored or worn cylinder walls.