GM Service Manual Online
For 1990-2009 cars only

Excessive oil consumption, not due to leaks, is the use of 1.9L (2 qts) or more of engine oil within 3 200 kilometers (2,000 mi). The causes of excessive oil consumption include the following conditions:

    â€¢ External oil leaks. Tighten bolts and/or replace gaskets and oil seals as necessary.
    â€¢ Incorrect oil level or improper reading of oil level indicator. With the vehicle on a level surface, allow adequate drain down time and check for the correct oil level.
    â€¢ Improper oil viscosity. Use recommended SAE viscosity for the prevailing temperatures.
    â€¢ Continuous high speed driving and/or severe usage.
    â€¢ Crankcase ventilation system restrictions or malfunctioning components.
    â€¢ Valve guides and/or valve stem oil seals worn, or the seal omitted. Ream guides and install oversize service valves and/or new valve stem oil seals.
    â€¢ Piston rings broken, improperly installed, worn, or not seated properly. Allow adequate time for rings to seat. Replace broken or worn rings as necessary.
    â€¢ Piston improperly installed or miss-fitted.