1997 Cadillac DeVille Owner's Manual - Page 305

What to Use Use a mixtureof one-half clean water (preferably distilled) and one-half DEX-COOL@coolant which won't damage aluminum parts. If you usethis mixture, you don't need to add anything else. I NOTICE: If you use an improper coolant mix, your engine could overheat and be badly damaged. The repair cost wouldn't be covered by your warranty. Too much water in the can freeze mix and crack the engine, radiator, heater core and other parts. Adding only plain water your cooling system to can be dangerous. Plain water,some other or liquid like alcohol, can boil before the proper coolant mix will. Your vehicle'scoolant warning system is set the proper coolant mix. With for plain wateror the wrong mix, your engine could get toohot but you wouldn't getthe overheat warning. Your engine could catch fire you or and others couldbe burned. Use a 50/50 mix of clean water andDEX-COOL@coolant. If you have to add coolant more than four times a year, have your dealer check your cooling system. I NOTICE: If you use the proper coolant, don't have to you add extra inhibitors or additives which claim to improve the system. These can be harmful. 6-22