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 TankBuying New Tires
GM has developed and matched specific tires for the vehicle. The original equipment
tires installed were designed to meet General Motors Tire Performance Criteria Specification
(TPC Spec) system rating. When replacement tires are needed, GM strongly recommends
buying tires with the same TPC Sp ...
Reporting Safety Defects to General Motors
In addition to notifying NHTSA (or Transport Canada) in a situation like this,
notify General Motors.
Call 1-800-222-1020, or write: Chevrolet Motor Division
Chevrolet Customer Assistance Center
P.O. Box 33170
Detroit, MI 48232-5170
In Canada, call 1-800-263-3777
(English) or 1-800-263-7854
...
Ride Control Systems
Traction Control/Electronic Stability Control
System Operation
The vehicle has a Traction Control System (TCS) and StabiliTrak®, an electronic
stability control system.
These systems help limit wheel slip and assist the driver in maintaining control,
especially on slippery road conditions.
T ...