So last month we took our rig out for its 4th adventure. Being an early spring the temps were getting up to the 70s and 80s. in GA. The tow vehicle is a 2000 Ford F150 extend cab 5 speed manual transmission. The truck is rated to tow 3,500 lbs. The trailer empty is 2,500 lbs. During our travels the temperature gauge kept rising especially when we were towing up hills. Believe me south GA along the "Fall Line" has pretty good hills. Even towing on the interstate with my foot heavy on the accelerator the gauge would rise to hot. If I back off the accelerator then the temp would go down. But then of course I would only be traveling at 55 mph. I'd like to be able to tow at 65 mph without any issue. I don't know if the thermostat is going bad or if I need one with a different temp rating?