I have run a 170 Deg T-Stat for over 3 years in my Flex. I return to Iowa at Christmas for at least a week every winter. I have noticed NO difference in heating up the engine & heater at any time. I also was running a 160 deg T-stat in my Denali XL for at least 6 years, and I had the same results. It will not affect the heater time. In both instances, I saw a 10 -15 degree drop in Coolant temp over stock T-stat. In the summer, when over 80 deg, it helps to have the fans come on sooner, to match the cooler T-stat, especially if you are at a strip. Otherwise, it really makes no difference from my experiences in 4 vehicles with 160-170 T-stats. Go for it. It is a much better investment than the AirAid...