I just had mine in for its 30K service to Isuzu dealer, and I supplied my 9 qts of royal purple, but they only used like 3.5-4 qts???
They did change it, if you look at the tranny pan, there is a drain right in the center, but a little ways up and still facing down is a fill hole, so basically your refilling whats in the pan up to that level. Is this correct, why did it take only 4 qts, is there a filter to change or a correct way to do this so I can clue my dealer in or do it myself? The owners manual says to "have your dealer service the auto trans".