2009 Chevrolet Express Van Owner's Manual - Page 267

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 6-15 for more information. 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 recovery tank. If the coolant inside the coolant recovery 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 COLD FILL mark, add a 50/50 mixture of clean, drinkable water and DEX-COOL® coolant at the coolant recovery tank, but be sure the cooling system is cool before this is done. When the engine is cold, the coolant level should be at or above the COLD FILL mark. If it is not, there could be a leak in the cooling system. If the coolant is low, add the coolant or take the vehicle to a dealer/retailer for service. 5-27