Does switching to a cooler stat REALLY hurt MPG?
I've heard a discussion on a local radio station recently where a mechanic stated that in todays modern, hotter running engines it was better to stick with the more common 195 degree OE temp stat to maintain better MPG and emission figures than switching to a cooler operating t-stat.
I was wondering if there is any truth to this notion? Has anyone felt that by switching to a cooler 180 stat their MPG or emission numbers have suffered, even slightly? It seems that by using the cooler running 180 or a hotter OE 195 there are good points and bad points to be made for each argument.