Recommended Fuel
Use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, an audible knocking noise, commonly referred to as spark knock, might be heard when driving.
If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If heavy knocking is heard when using gasoline rated at 87 octane or higher, the engine needs service.
See also:
Navigation
OnStar navigation requires the Directions and Connections service plan.
Push to receive directions or have
them sent to the vehicle navigation screen. Destinations can also be forwarded to
the v ...
If No Steam is Coming from the Engine Compartment
If an engine overheat warning is displayed but no steam can be seen or heard,
the problem may not be too serious. Sometimes the engine can get a little too hot
when the vehicle:
○ Climbs a ...
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 the vehic ...