See also:

When the Change Engine Oil Soon Message Displays
Change engine oil and filter. See Engine Oil . An Emission Control Service. When the CHANGE ENGINE OIL SOON message displays, service is required for the vehicle as soon as possible, within the next ...

Engine Coolant Heater
The engine coolant heater can provide easier starting and better fuel economy during engine warm-up in cold weather conditions at or below 0°F (−18°C). Vehicles with an engine coolant he ...

Diagnostics
OnStar Vehicle Diagnostics will perform a vehicle check every month. It will check the engine, transmission, antilock brakes, and major vehicle systems. It also checks the tire pressures, if ...