I have seen some in the past as well but they were taking out a heavy
oil and replacing it with a lighter one. I guess if you do not mind all the noise and gear clashing it is worth it. I could put a light weight
oil in the trans I build as well but if the trans was made for a heavy
oil I am sticking with it. I just kind of figure the folks that designed it to start with probably had a good idea of what it should have in it.