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:

California Proposition 65 WarningInterior Lighting
Dome Lamps
The dome lamp controls are in the headliner above the rear seats.
: Press to turn the lamps off, even
when a door is open.
: When the button is returned to
the middle position, the lamps turn on automatically when a door is opened.
: Press to turn on the dome lamps.
Reading ...
Engine Oil
To ensure proper engine performance and long life, careful attention must be
paid to engine oil. Following these simple, but important steps will help protect
your investment:
Always use engine oil approved to the proper specification and of the proper
viscosity grade. See “Selecting th ...
Door Lock and Ignition Lock Folding and Non-Folding Key Cutting
High Security keys are available from the service parts system.
Obtain the key code from the security card or from the GM Dealer World, Parts,
Key Code Look Up system.
If you have the key code and access to a Triax-E., BD Laser or other code key
cutting machine from the GM Dealer Equipment C ...