changing rear and tranny fluid, what's the best?

[Bartruff1]

I can't imagine why you would change them..but...it is your car...

[D111]

few years old with a few thousand miles but it's the original fluids I believe.

I remember speaking to backdrift in Florida and them tell me they like to change the fluids once a year or so but it's not mandatory.

I figured can hurt to put premium fluids and get rid of the originals?