1998 Pontiac Sunfire Owner's Manual - Page 269

~ NOTICE: When adding coolant, it is important thatyou use onlyDEX-COOL@(silicate-free) coolant. If coolant other thanDEX-COOL is added to the system, premature engine, heater core or radiator corrosion may result.In addition, the engine coolantwill require change sooner at 30,000 miles (50 000 km)or 24 months, whichever occurs first. Damage causedby the use of coolant other than DEX-COOL@ is not covered byyour new vehiclewarranty. What to Use Use a mixture of one-half clean water (preferably distilled) and one-half DEX-COOL@coolant which won't damage aluminum parts. If you use this mixture, you don't needto add anything else. -- I 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 mixture will. Your vehicle's coolant warning system is set for the proper coolant mixture. With plain water or the wrong mixture, your engine could get too but you wouldn't hot get the overheat warning. Your engine could catch fire and you or otherscould be burned. Use a 50/50 mixture of clean water and DEX-COOL@coolant. I