Your vehicle is equipped with GM's Engine Oil Life Monitoring System. When the CHANGE ENGINE OIL message comes on, have your vehicle serviced as soon as possible within the next 600 miles. It is possible that based on driving habits and conditions; the system may not indicate that vehicle service is necessary for more than a year. However, your engine oil and filter must be changed at least once a year and at this time the system must be reset.
The necessary services, checks and inspections are grouped into two schedules: Maintenance I and Maintenance II. GM recommends starting with the Maintenance I schedule; the second should be Maintenance II, and then alternating between I and II thereafter. However, always use Maintenance II whenever the message comes on ten months or more since the last service or if the message has not come on at all for one year.