1993 Buick Regal Owner's Manual - Page 197

How to Add Coolant to the Coolant Recovery Tank If you haven't found a problem yet, but the coolant leveI isn't at or above "COLD" add a 50/50 mixture of clean water (preferably distilled) and a proper antifreeze at the coolant recovery tank. (See "Engine Coolant'' in the Index for more information aboutthe proper coolant mix.) m - u m w - . - frc anc engine, radiator, heatercore and other-parts. Use the recommended coolanl In cold weath :an wate can bedangerous. Plain water, or some othe liquid likealcohol, can boil before theprope coolant mix will. Your vehicle's coolant warn system is set for the proper coolant mix. Wit plain water or the wrong mix, your engine could get too hot but you wouldn't the overheal get warning. Your engine could catch fire and you or others could be burned. Use a 50/50 mix o clean f water and a proper antifreeze