1993 Pontiac Firebird Owner's Manual - Page 196

If there seems to be no leak, check see to if the electric engine fanis running. If the engine is overheating, the fan should be running. If it isn't, your vehicle needs service. How to Add Coolant to the Coolant Recovery Tank If you haven't found a problem yet, but the coolant level isn't at QT above FULL COLD, add a SQ/50mixture of clean water (preferably distilled) and a proper antifreeze at the coolant recovery tank. (See "Engine Coolant" in the Index for more information about the proper coolant mix.) Adding only plain waterto your cooling system can be dangerous. Plain water, or some other liquid like alcohol, can boil before the proper coolant mix will. Your vehicle's coolant warning system is set for the proper coolant mix. With plain water or the wrong mix, your engine could get too hot but you wouldn't get theoverheat warning. Your engine could catch fire and you or others could be burned. Use a 50/50 m'ixof clean water and a proper antifreeze. I 195 = =