2007 Chevrolet Monte Carlo Owner's Manual - Page 329

If you have not found a problem yet, but the coolant level is not at the cold fill line, add a 50/50 mixture of clean, drinkable water and DEX-COOL® engine coolant at the coolant recovery tank. See Engine Coolant on page 320 for more information. Notice: In cold weather, water can freeze and crack the engine, radiator, heater core and other parts. Use the recommended coolant and the proper coolant mixture. If the overheat warning continues, there is one more thing you can try. Add the proper coolant mixture directly to the cooling system through the coolant fill neck on the engine, but be sure the system is cool before you do it. {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 radiator pressure cap - even a little - they can come out at high speed. Never turn the cap when the cooling system, including the radiator pressure cap, is hot. Wait for the cooling system and radiator pressure cap to cool if you ever have to turn the pressure cap. {CAUTION: You can be burned if you spill coolant on hot engine parts. Coolant contains ethylene glycol and it will burn if the engine parts are hot enough. Do not spill coolant on a hot engine. When the coolant level in the coolant recovery tank is at the cold fill line, start the vehicle. 329