Hi:
It seems that my radiator cooling fan starts to run shortly after I start and run the car for a few miles. This happens even when it is below zero out there, and I am driving on the highway.

I flushed the radiator really well...that did not help. I have a high performance themostat that I want to try, but want to make sure I have checked other things too. Is it a relay or switch problem? The guage needle is usually in the middle of the cold and hot zone.

Could this be related to low gas mileage in any way? Any ideas?
Thank you in advance.
Shawn