Oil Life Monitor
WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
Engine Oil life % is based on the information the DIC receives from a class 2 message from the PCM. The DIC displays the current % of the GM Oil Life System. When the oil life index as less than 10%, the CHANGE OIL SOON light will be illuminated in the IPC indicating the oil needs changing.
When the oil is changed the Oil Life Monitor will need to be reset, to OIL CHANGE REMINDER in General Information. The value of this mode is retained during Ignition OFF.