1993 Oldsmobile 88 Owner's Manual - Page 238

I What to Use: Use a mixture one-half clean water of (preferably distilled) and one-half antifreeze that meets"GM Specification 1825M," which won't damage aluminum parts. You can also use a recycled o coolant conforming t GM Specification 1825M with a complete coolant flush and refill. Also use GM Engine Coolant Supplement (sealer) with any complete coolant change. If you use these, you don't need to add anything else. Adding only plain water to your cooling system can be dangerous. Plain water, or some other liquid like alcohol, can boil before the proper coolant will. mix Your vehicle's coolant warning system is set for the proper coolant mix. With plain wateror the wrong mix, your engine could get too hot but you wouldn't get the overheat warning. Your engine could catch fue and you or others 50150 mix could be burned. Use a of clean water and a proper antifreeze. 237