The fluid was contaminated with engine coolant.
What to take away from all this ... the transmission fluid looked absolutely clean when I looked at it at the first repair shop and the fluid was not tested there. So, if your coach is an older unit, next time you check the transmission fluid HAVE IT TESTED FOR CONTAMINATES! 0.2% is a very small amount. !
Sorry to hear of your troubles. At least you have it figured out now.
Testing the transmission oil every year is a good idea (I do that now just to let me know when to change the fluid). But if the test comes back showing signs of coolant in the oil, its already too late and a rebuild is needed (according to Allison).
I wonder if there is an
oil-to-air cooler (rather than the oil-to-coolant cooler used now) that would work.
At least with an oil-to-air there is no chance of getting coolant in the transmission (and a leaking cooler will show up as an oil leak on the ground). I guess it depends on how much surface area the cooler would require, and how much space is available to mount that type of cooler.
