My thermostat gauge is reading above red, but my car is not over heating, i can let the car sit for a week start it and the guage will slowly progress up to the red, i drove 1500 miles like this and it didnt over heat, coolant is still filled up. I changed my thermastat and no smoke comes out of the car.

any ideas?

 

Check the temperature sending unit on the head. It's the one wire skinny connector. I have seen corrosion cause this. Also, the sending unit may be out of specification.