I just drove my car for about 60 miles and the temp guage never moved out of the blue area. Then I hit some traffic and in a few minutes the neddle moved almost to the the middle. The temperature outside was in the hight 30's (first cold day in area) What could be causing this? Can thermostat be stuck open? Coolant too strong (not enough water) Any other ideas? I need to take care of this as I'm not going to have heat in the car with temp this low. TIA DanC