Originally Posted by JCL

Yes. Your transmission has systems that adapt to the characteristics of the fluid that it has in it (the fluid characteristics that change over time, like viscosity and frictional characteristics for clutch engagement). Until the fluid is outside the range that the transmission can handle, there is no benefit to changing it. The transmission won't know the difference. It isn't a lubrication issue, since lubrication places such a low demand on the fluid.

If you want to do it, fine, go for it. Just don't try and claim that it is for the benefit of the transmission. It is for your feelings of having done something.