GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

Worn valves, valve guides and/or valve stem oil seals

    â€¢ Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection in Engine Controls - 2.5L.
    â€¢ Repair or replace as required.

Worn Piston Rings

(Oil consumption may or may not cause the engine to misfire.)

    â€¢ Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection in Engine Controls 2.5L.
    â€¢ Inspect the cylinders for a loss of compression. Refer to Engine Compression Test .
    â€¢ Perform cylinder leak down and compression testing to determine the cause.
    â€¢ Repair or replace as required.