GM Service Manual Online
For 1990-2009 cars only
    â€¢ Low oil level. Fill to full mark on oil level indicator.
    â€¢ Incorrect or malfunctioning oil pressure switch
    â€¢ Incorrect or malfunctioning oil pressure gauge
    â€¢ Improper oil viscosity for the expected temperature
    â€¢ Oil pump worn or dirty
    â€¢ Malfunctioning oil pump pressure regulator valve
    â€¢ Plugged oil filter
    â€¢ Oil pump screen loose plugged, or damaged
    â€¢ Excessive bearing clearance. Replace as necessary.
    â€¢ Cracked, porous or restricted oil galleries. Repair or replace block.
    â€¢ Oil gallery plugs missing or incorrectly installed. Install plugs or repair as necessary.
    â€¢ Oil diluted by moisture or unburned fuel