Oil Change Reminder Lamp: Description and Operation

WHEN TO CHANGE ENGINE OIL
Your vehicle has a computer that lets you know when to change your engine oil. This is not based on mileage, but on engine revolutions and engine operating temperature. When the computer has calculated that the oil needs changing, the GM Oil Life System will indicate that a change is necessary. The mileage between oil and filter changes will vary depending on how you drive your vehicle - usually between 3,000 miles (5,000 km) and 12,000 miles (20,000 km) since your last oil and filter change. Under severe conditions, the system may come on before 3,000 miles (5,000 km). Never drive your vehicle more then 12,000 miles (20,000 km) or 12 months (whichever occurs first) without an oil change.
The system won't detect dust in the oil. So if you drive in a dusty area, be sure to change your oil and filter every 3,000 miles (5,000 km) or sooner.