Oil Life Left
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
Oil life left percentage is based on the information the DIC receives from a class 2 message from the PCM. The DIC displays the current percentage of the GM Oil Life System. When the oil needs changing the change engine oil indicator in the message center turns ON. When the engine oil is changed, reset the oil life left. Refer to GM Oil Life System - Resetting in Maintenance and Lubrication.