Re: Best type of thermostat for 5.0 Reply #15 – April 10, 2005, 01:20:20 PM I have a 180* in my cougar (which I don;t drive in winter) and I noticed a tiny drop in MPG, over a few tanks, however perhaps this may caused by other modifications. My tempo, on the other hand, lost 3-4mpg, but that is a differnent (hotter running) engine. MPG should not be a big deturant from the 180*. I guess the heat thing varies by car. A few years ago I put a 180* Autorad thermostat in my tempo and later my truck, and come winter the heater performance was noticibly diminished in both. Keep in mind I probably live in the coldest climate of all the members here, so this may not be a factor for anyone else. At temps below minus 25*c the air comming out of the vents was not nearly as hot as before. At -40* and colder I was freezing. (This is with modifications to run at the temp. and letting the vehical warm up for 30-45min ) Quote Selected