1996 Buick Century Owner's Manual - Page 229

What to Use Use a mixture of one-half clean water (preferably distilled) and one-half DEX-COOL TM (orange-colored, silicate-free) antifreezethat meets GM Specification 6277M, which won't damage aluminum parts. Use GM Engine Coolant Supplement (sealer) (GM Part No. 3634621) with any complete coolant change.If you use this 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 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 dealer check your cooling system. lain water to your cooling system can be dangerous. Plain water, or some other liquid like alcohol, can boil before the proper coolant mix will. Your vehicle'scoolant warning system is set for the proper coolant mix. With plain water or the wrong mix,your engine could get toohot but you wouldn't getthe 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 (orange-colored, silicate-free) antifreeze. TM NOTICE: If 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. 6-23