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 TankEvent Data Recorders
This vehicle is equipped with an event data recorder (EDR). The main purpose
of an EDR is to record, in certain crash or near crash-like situations, such as
an air bag deployment or hitting a road obstacle, data that will assist in understanding
how a vehicle’s systems performed. The EDR is de ...
Ignition Positions
The ignition switch has four different positions.
The uplevel key must be fully extended to start the vehicle.
To shift out of P (Park), the ignition must be in ON/RUN and the regular brake
pedal applied.
1 (STOPPING THE ENGINE/LOCK/ OFF): When the vehicle is stopped, turn the ignition
sw ...
Connections
The required specific Onstar subscription plan includes the services that follow
to help customers stay connected.
For coverage maps, see www.onstar.com (U.S.) or www.onstar.ca (Canada).
WiFi Connectivity (If Equipped)
The vehicle has a WiFi hotspot that provides a high-speed, wireless Internet ...