I don't use scangauge as a fuel efficiency tool... but I do use my truck for "very rough service" in Arizona - and transmissions are expensive. When the trans fluid is over ~210 or so, I stop & idle (only happens on long/steep inclines now that a large aux. cooler is fitted) - the factory equipped warning lamp only illuminates when trans temp exceeds 290F
- juice doesn't last long at that kind of temp
