The vehicle must be on a level surface when checking the coolant level.
It is normal to see coolant moving in the upper coolant hose return line when the engine is running.
Check to see if coolant is visible in the coolant surge tank. If the coolant inside the coolant surge tank is boiling, do not do anything else until it cools down.

If coolant is visible but the coolant level is not at or above the mark pointed to, add a 50/50 mixture of clean drinkable water and DEX-COOL coolant.
Be sure the cooling system is cool before this is done.
What to Use
How to Add Coolant to the Coolant Surge TankUsing the Preset Buttons
Up to seven favorites pages can be saved, and each page can store up to five
channels.
To change a preset button, tune to the new desired channel and hold the button.
Listening to Preset Channels
Continue pressing or
to select the desired favorites
page.
Press the preset button ...
Hazard Warning Flashers
The hazard warning flasher button is on the center stack.
(Hazard Warning Flasher): Press
to make the front and rear turn signal lamps flash on and off.
This warns others that you are having trouble. Press the button again to turn
the flashers off.
When the hazard warning flashers are on, ...
OnStar Overview
Voice Command Button
Blue OnStar Button
Emergency Button
This vehicle may be equipped with a comprehensive, in-vehicle system that can
connect to a live OnStar Advisor for Emergency, Security, Navigation, Connection,
and Diagnostic Services. OnStar services may require a paid subscripti ...