1996 Cadillac DeVille Owner's Manual - Page 245

NOTICE: In cold weather, water can freeze and crack the engine, radiator, heater core and otherparts. So use the recommended coolant. A A CAUTION: You can be burned if you spill coolant on hot engine parts.Coolant contains ethylene glycol hot and itwill burn if the engine parts are enough. Don't spill coolant on a hot engine. 1. You can remove the coolant surgetank pressure cap when the cooling system, including the coolant surge tank pressure cap and upper radiator hose, is no longer hot. Turn the pressurecap slowly counterclockwise until it first stops. (Don't press down while turning the pressure cap.) If you hear a hiss, wait for thatto stop.A hiss means there isstill some pressure left.