I know I run the risk of starting an argument, but here goes. I have tried a 180 in my rig, and found that in real hot temps/slow speeds, eventually I would overheat. But, with a 195 in it, I stopped that mess. I figure, with the higher temp, it keeps the water from circulating so much, that it has time to dissipate some heat in the radiator. I sort of confirmed this with a infrared thermometer, and found that the radiator cycled from about 180 to 200 on opening and closing of the t-stat. This was at the fins closest to the inlet of the radiator, and idling in my driveway at about 90 deg ambient temp.