I'm in need of a tranny fluid change, but dont know what to get, because of a number of factors...

a. i hear that non motor oil type fluid kills B-series trannies
b. only honda mtf is recommended from factory
c. i've heard many gooood opinions on Redline and Royal purple fluids

I'd like to go for the Royal Purple, because i felt it in my friend's Rx7, before and after, and it was a HUGE difference in smoothness, and engagement. The problem is that Royal Purple is hard to find, and I dont know if they offer a Honda compatible fluid weight. Any help is apreciated....thanks in advance