1997 Oldsmobile Cutlass Supreme Owner's Manual - Page 240

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