I believe the pathfinder has this part because it is ideal when the engine is under constant heavy load (i.e. towing some ****). I dont see how there would be any negative effect to better coolant distribution for a FI'd car.

 

my 3rd fill up since the install. All three times I've gotten 19.7mpg or better (less than 20mpg, though). I have not seen anything over 17.5 for years (only around the time with a fresh engine build). This is weird, but I'm not complaining. Also running 20 deg. cooler consistently.

 

air temps have also gone down 30* since august.....

when tracking fuel mileage you have to fill only at the same station every time so you know the pump kicks off at the same backpressure (same amount of fuel in the tank) as well as the same quality of gas over other brands. To get best average you have to drive until the tank is almost empty before filling up again.

I tracked fuel mileage with different brands. I did above testings over a course of a full year of recording it to get a baseline average before switching. There are so many factors that 3 tanks of fuel (which are probably different stations) isn't near enough info to say you are getting better gas mileage.

 

I've measured my mpg 100s of times. I know my car.
It never once hit 18+ for a very long time. not even over 17.8 on a
30 below zero degree weather with industrial size fan mounted in the front.

 

that's a pretty stupid comment to make because you actually lose gas mileage in the cold so it really doesn't help prove that your 3 fill ups are solid evidence.

 

the best cheap cooling mod would probably be a higher amount of water in your cooling system. running 3/4 water will help the cooling system alot more than a thermostat. of course if you live where it gets near freezing, this is just all bayud.

 

its commonly believed that cooler is better, while actually quite the opposite is true. hotter cars have more complete combustion, ie better mileage.....

of course, thats all based on limits of octane, etc etc, but in general hotter is better.