GM Service Manual Online
For 1990-2009 cars only
    â€¢ Low oil level. Fill to full mark on oil level indicator.
    â€¢ Slow idle speed.
    â€¢ Incorrect or malfunctioning oil pressure switch.
    â€¢ Incorrect or malfunctioning oil pressure indicator.
    â€¢ Improper oil viscosity or diluted oil.
         Install oil of the proper viscosity for expected temperature. Install new oil if diluted with moisture or unburned fuel mixture.
    â€¢ Oil pump worn or dirty.
    â€¢ Plugged oil filter.
    â€¢ Oil pickup screen loose or plugged.
    â€¢ Hole in oil pick up tube.
    â€¢ Excessive bearing clearance. Replace as necessary.
    â€¢ Cracked, porous or restricted oil galleries. Repair or replace block.
    â€¢ Gallery plugs missing or misinstalled. Install plugs or repair as necessary.
    â€¢ Malfunctioning oil pump pressure regulator valve.
    â€¢ Camshaft worn or poorly machined. Replace the camshaft.
    â€¢ Worn valve guides.