1998 Buick Century Owner's Manual - Page 240

NOTICE: In cold engine, Use the coolant weather, water can freeze and crack the radiator, heater core and other parts. recommended coolant and the proper mixture. A CAUTION: You can be burned you spill coolant on hot if engine parts. Coolant contains ethylene glycol and itwill burn if the engine parts are hot on enough. Don't spill coolant a hot engine. When the coolant in the coolant recovery tank is at the COLD mark, start your vehicle. If the overheat warning continues, there's one more thing you can try. You can add the proper coolant mixture directly to the radiator, but be sure the cooling system is cool before you do it. 5-20