Replace thermostat on 2003 grand prix gtp with

The thermostat housing is located in the upper radiator hose. You will see a metal elbow secured by two bolts into what I remember is the upper intake manifold...don't quote me on that but you will see it regardless of whatever I call it. Anyways, GM decided it was a good idea to put stainless steel bolts in there but that makes it easy to strip the threads in the bolt hole so I think it's best when you put your wrench on the bolt to just tap on the handle till you vibrate it loose, then turn it.
When you pull off the housing you'll lose a little coolant and it will create an air pocket which we'll address. It's a 50/50 chance that the thermostat housing gasket will either stick to the housing or the engine...it may be torn, cracked or flaking in either case clean both contact surfaces before you replace the gasket. I recommend an oil impregnated poly material gasket.
Note the position of the thermostat in the hole and place the new one in as such.
I recommend a 180 degree thermostat...stock is 195 but the GTP runs better with the 180.
Put on gasket and reinstall the hose/housing assembly, alternate from one bolt to the other so the housing mates flat and cannot cause a leak.
Next, fill the coolant overflow bottle to the "HOT" mark. If the bottle is dirty and hard to see just put a light on top of the bottle...GM didn't mark it very well so if it's not squeaky clean you can hardly see a damn thing.
*IMPORTANT** if your car still has Dexcool in it, DUMP IT. It will eventually destroy the motor.
If not...continue on. Start the car. Go back to the thermostat housing and place a rag on top of, and twist the peacock valve on top of it to let the air out until it starts to get coolant on the rag. Done.