2010 f250 4wd diesel. 36000 miles. I am having to add 1/2-1 pint of transmisson fluid every 500 miles or so. I had it serviced at about 25,000 miles because i am pulling a fifth wheel RV. I have had it in the dealership and they can find nothing at all. I see no leaks either. No one seems to know where it its going? It has been suggested that the seals could be bad and it is going into the transfer case? Any ideas?