Okay, I am sure this is simple, but I have been unable to find information on how to reset the change oil message on my 2002 denali. Driving me crazy ! Thanks in advance.

I'm not sure if this works on the 2002, but try this:

Turn the ignition key to the RUN position. Fully push and release the accelerator pedal 3 times within 5 seconds. If the CHANGE OIL SOON light flashes 2 times, the system is reset. However, if the light comes on and stays on for 5 seconds, the system did not reset. Repeat the procedure if the system does not reset.

Ditto for the 2001 Yukon XL.