How do you bleed the cooling system of a 2004 Pontiac grand prix gt?

First remove the plastic engine cover by un-screwing the oil filler neck from the engine (not just the cap but the whole tube). Lift off cover. Then find the thermostat housing (follow large hose coming from top of radiator). Get a rag or towel so coolant doesn't splash on you. Locate the bleeder screw on top of the thermostat housing (10mm screw). Run the engine for 5 mins. or so until it gets up to temperature. Leave engine running and slowly turn the bleeder screw counter-clockwise until only coolant is coming out. Re-tighten screw and replace engine cover. I just replaced the thermostat on my '04 so I know it works.

I just did this and the screw is a two piece screw, the 10 mm part need not be turned on my car ('04 GP GT2), instead the top part of the screw which was a 7 mm is to be turned to let the system bleed off.