Burl, my manual says that the GM oil life system is:
Your vehicle has a computer system that lets you know when to change engine oil and filter. This is based on engine revolutions and engine temperature and not mileage. If you are driving under the best conditions the oil life system may not indicate that an oil change is necessary for over a year. However, your oil and filter must be changed at least once a year and at that time the system must be reset.
To reset the system
1) Turn the ignition key to the run position with the engine off
2) Fully depress and release the accelerator pedal three times within 5 seconds.
3) If the change engine oil light flashed for 5 seconds , the system is reset.