Reactivation for Subsequent Owners
Push 
and follow the prompts to speak to an Advisor as soon as possible after acquiring the vehicle.
The Advisor will update vehicle records and will explain the OnStar service offers and options available.
See also:
Transferring Service
Push to request account transfer
eligibility information. The Advisor can assist in canceling or removing account
information. If OnStar receives information that vehicle ownership has changed,
...
What to Use
WARNING
Adding only plain water or some other liquid to the cooling system can be dangerous. Plain water and other liquids, can boil before the proper coolant mixture will.
The coolant warning syste ...
General Information
For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:
...