GM Oil Life System Resetting: Notes
When the system has calculated that oil life has been diminished, it will indicate that an oil change is necessary. A CHANGE ENGINE OIL SOON message will come on. Change the engine oil as soon as possible within the next 1 000 km (600 miles). It is possible that, if driving under the best conditions, the oil life system may not indicate that an oil change is necessary for over a year. However, the engine oil and filter must be changed at least once a year and at this time the system must be reset.
If the system is ever reset accidentally, change the engine oil at 5 000 km (3, 000 miles) since last oil change.