This is what GM says:quote:Originally posted by ADFD1:
If API certification, the proper grade of oil, and the recommended interval didn't matter then the OM would most likely read something like this. Add what ever oil you want, run it as long as you want, just keep it full.
“The New Vehicle Warranty would not be void simply because an owner failed to use proper engine oils or did not perform maintenance at the prescribed intervals. Warranty applicability is contingent upon the cause of failure.”
Service Policies and Procedures Department,
General Motors Corporation “