2003 Pontiac Montana Owner's Manual - Page 345

What to Use Use a mixture of one-half clean, drinkable water and one-half DEX-COOL@ coolant which won't damage aluminum parts. If you use this coolant mixture, you ' n't need ' ad(' 'hing else. If you have to add coolant more than four times a year, have your dealer check your cooling system. Notice: If you use the proper coolant, you don't have t o add extra inhibitors or additives which claim to improve the system.These can be harmful. Checking Coolant The engine coolant reservoir is located on the driver's side of the vehicle, above the engine air cleaner/filter. See Engine Compartment Overview on page 5-12 for more information on location. Adding only plain water to your cooling system can be dangerous. Plain water, or some other liquid such as alcohol, can boil before the proper coolant mixture will.Your vehicle's coolant warning system is set for the proper coolant mixture. With plain water or the wrong mixture, your engine could get too hot but you wouldn't get the overheat warning. Your engine could catch fire andyou or others could be burned. Use a50/50 mixture of clean, drinkable water and DEX-COOL@coolant. Notice: If you use an improper coolant mixture, your engine could overheat and be badly damaged. The repair cost wouldn't be covered by your warranty. Too much water in the mixture can freeze and crack the engine, radiator, heater core and other parts. 5-24 The vehicle must be on a level surface. When your engine is cold, the coolant level should be at the FULL COLD mark, or a little higher. When your engine is warm, the level should be above the FULL COLD mark or a little higher.