I have talked to ford dealers and asked them about manual trans temp gages and thay told me that it was not nessary at all. The fluid that ford says to use is a costly but a quite effictve and as long as long as you use it you will be fine. Don't worry about the small stuff. I pulled a 38 ft fifth wheel in July thru texas and it did just fine and I have a 450 so I have some deep gears.