So I bought this car brand new and up until a few months ago the temp gauge ran exactly in the middle-all of the time. But now it seems the temp gauge is running up to the next line past half way. It doesn't matter if it is cold out or if I am running down hill. It eventually goes back down to half way, especially if I turn on the heater. I took the car in the other day thinking the thermostat was bad but they ran it through 5 cycles and all they could find was the upper radiator hose was a little loose. Well, its still running what I consider to be hot. I put new Dexcool in a few months ago and the car has about 282,000 miles on it. The radiator is about 2 years old as well. Any ideas on what could be making it run warm like that? They told me the normal operating temp is about 217 degrees and that is what they measured as well. Thanks!