The engine heater can provide easier starting and better fuel economy during engine warm-up in cold weather conditions at or below -18°C (0°F). Vehicles with an engine heater should be plugged in at least four hours before starting.

It is shipped from the factory with a tie holding it in place. Use care in removing the tie so that the cord is not damaged.
Check the heater cord for damage. If it is damaged, do not use it. See your dealer for a replacement. Inspect the cord for damage yearly.
Warning
Improper use of the heater cord or an extension cord can damage the cord and may result in overheating and fire.
Failure to use the recommended extension cord in good operating condition, or using a damaged heater or extension cord, could make it overheat and cause a fire, property damage, electric shock, and injury.
Keep the cord away from any moving parts.
If you do not it could be damaged.
The length of time the heater should remain plugged in depends on several factors. Ask a dealer in the area where you will be parking the vehicle for the best advice on this.
Starting the Engine
Retained Accessory Power (RAP)New Vehicle Break-In
Caution
The vehicle does not need an elaborate break-in. But it will perform
better in the long run if you follow these guidelines:
Do not drive at any one constant speed, fast or slow, for
the first 805 km (500 mi).
Do not make full-throttle starts. Avoid downshifting to brake or slow t ...
Charging System Light
This light will come on briefly
when the ignition is turned on, and the engine is not running, as a check to show
it is working.
It should go out when the engine is started. If it stays on, or comes on while
driving, there may be a problem with the electrical charging system. Have it checked ...
OnStar Additional Information
Transferring Service
Press to request account transfer
eligibility information. The Advisor can assist in canceling or removing account
information.
Selling/Transferring the Vehicle
Call 1-888-4-ONSTAR immediately to terminate your OnStar services if the vehicle
is disposed of, sold, trans ...