I have the same problem and mine is running almost to the danger 260 mark on my gauge? I've changed the thermostat, flushed it out and added new coolant, checked for debris, and took off the radiator reservoir and disconnected the hoses to the heater core to make sure it wasn't clogged either. And if this isn't strange enough when I turn on the heater/defroster it blows cold air as if the a/c was on?? Totally confused because it also uses tranny fluid (6-speed) at a rate of every four days I have to fill up and have no leaks under the car??? I have the auto climate control.