Originally Posted by meborder

There is a lot of bad info in this thread....

The 6r80 has an internal thermostat which controls the minimum temperature at which the transmission will run. That is why they all run in the upper 190's with no load in warm weather. The coolers are very effective also, which is why they don't seem to run much hotter when towing.

The stock transmission temp gauge only has 4 positions. "cold" which it displays below 50 degrees F, "normal" which is in the middle of the normal range which it displays from 50 to 220 degrees F, "elevated" where the needle points to the yellow zone on the gauge which is displayed from 230 to 250 degrees F, and "danger" where the needle points to the red above 250 degrees. Those are the only programmed needle positions for the gauge.

The gauge is programmed for a slow sweep, so If your needle is higher than usual but not quite to the yellow, the trans has exceeded 220 and the needle is working its way to the yellow. If it is hanging out below the yellow, you are probably exceeding 220 but then cooling back down below 220 before the needle settles in the yellow zone.

Ford's standard is up to 220 is normal and you can run all day at that temp, and you can run up to 250 for up to 30min at a time. You should not exceed 250 if at all possible as there are some internal components that dont like to behave properly above 250.

These all come from our resident ford transmission guru Mark Kovalsky. Search for his numerous posts on transmission temps to get it straight from the horse's mouth.

Hope it helps.