2010 Hummer H3 Owner's Manual - Page 285

Vehicle Care 10-19 Engine Coolant The cooling system in the vehicle is filled with DEX-COOL® engine coolant. This coolant is designed to remain in the vehicle for five years or 240 000 km (150,000 miles), whichever occurs first. The following explains the cooling system and how to check and add coolant when it is low. If there is a problem with engine overheating, see Engine Overheating on page 10‑22. . WARNING (Continued) With plain water or the wrong mixture, the engine could get too hot but you would not get the overheat warning. The engine could catch fire and you or others could be burned. Use a 50/50 mixture of clean, drinkable water and DEX-COOL® coolant. Use a 50/50 mixture of clean, drinkable water and DEX-COOL coolant. If using this mixture, nothing else needs to be added. This mixture: ... Protects against rust and corrosion. Will not damage aluminum parts. Helps keep the proper engine temperature. What to Use 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 11‑8 for more information. { WARNING Adding only plain water to the cooling system can be dangerous. Plain water, or some other liquid such as alcohol, can boil before the proper coolant mixture will. The vehicle's coolant warning system is set for the proper coolant mixture. (Continued) Gives freezing protection down to −37°C (−34°F), outside temperature. Gives boiling protection up to 129°C (265°F), engine temperature. .