2005 Chevrolet Cobalt Owner's Manual - Page 245

Adding Coolant to the Intercooler System Fill Neck If coolant is not visible in the fill neck, add a 50/50 mixture of clean, drinkable water and DEX-COOL® coolant at the fill neck, but be sure that the cooling system, including the fill neck pressure cap, is cool before you do so. {CAUTION: Adding only plain water to your intercooler system can be dangerous. Plain water, or some other liquid such as alcohol, can boil before the proper coolant mixture will. With plain water or the wrong mixture, your engine could get too hot. Your engine could catch fire and you or others could be burned. Use a 50/50 mixture of clean, drinkable water and DEX-COOL® coolant. Notice: In cold weather, water can freeze and crack the engine, intercooler, and other parts. Use the recommended coolant and the proper coolant mixture. {CAUTION: Steam and scalding liquids from a hot cooling system can blow out and burn you badly. They are under pressure, and if you turn the intercooler system pressure cap - even a little - they can come out at high speed. Never turn the cap when the intercooler system, including the intercooler system pressure cap, is hot. Wait for the intercooler system and intercooler system pressure cap to cool if you ever have to turn the pressure cap. 5-27