1996 Buick Park Avenue Owner's Manual - Page 231
1996 Buick Park Avenue Manual
Page 231 highlights
Horn ) . , Add CL=-~=-to the Radiator 2. Then keep turning the pressure cap, but now push down as you turn it. Remove the pressure cap. 1. You can remove the radiator pressure cap when the cooling system, including the radiator pressure cap and upper radiator hose, is no longer hot. Turn the pressure cap slowly counterclockwise until it first stops. (Don't press down while turning the pressure cap.) If you hear a hiss, wait for that to stop. A hiss means there is still some pressure left. 5-19