2010 Chevrolet Avalanche Owner's Manual - Page 442

... Protects against rust and corrosion. Will not damage aluminum parts. Helps keep the proper engine temperature. Notice: If an improper coolant mixture is used, the engine could overheat and be badly damaged. The repair cost would not be covered by the vehicle warranty. Too much water in the mixture can freeze and crack the engine, radiator, heater core, and other parts. Notice: If extra inhibitors and/or additives are used in the vehicle's cooling system, the vehicle could be damaged. Use only the proper mixture of the engine coolant listed in this manual for the cooling system. See Recommended Fluids and Lubricants on page 7‑11 for more information. If coolant is visible but the coolant level is not at or above the FULL COLD mark, add a 50/50 mixture of clean, drinkable water and DEX-COOL® coolant at the coolant surge tank, but be sure the cooling system is cool before this is done. Checking Coolant The vehicle must be on a level surface when checking the coolant level. 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. The coolant surge tank is located in the engine compartment on the passenger side of the vehicle. See Engine Compartment Overview on page 6‑14 for more information on location. The coolant level should be at or above the FULL COLD mark. If it is not, you may have a leak in the cooling system. 6-28