1999 Buick Regal Owner's Manual - Page 222

yellowblue 4. After the engine cools, open the coolant air bleed valve. 5. Fill the radiator with the proper DEX-COOLR coolant mixture, up to the base of the filler neck. (See "Engine Coolant" in the Index for more information about the proper coolant mixture.) There is one bleed valve. It is located on the thermostat housing. If you see a stream of coolant coming from an air bleed valve, close the valve. Otherwise, close the valve after the radiator is filled. 6. Rinse or wipe any spilled coolant from the engine and the compartment. 5-18