I put a torque cool fan clutch on mine when I first got it since the OEM one was shot. It was from autozone or advance for <100 bucks IIRC. I think it is supposed to have a thermostat, but this one doesn't. It sounds awesome! My truck has a very distinctive sound, like a semi truck in the first 3 or 4 gears. On the trail, everyone knows my truck by sound alone, a faint ticking, a roar of fan and a decent rumble from the flowmaster 40. I am sure the fan affects my mpg, but I don't care, worth it just for the sound...lol.