[tickerguy]

Redline MTL is an acceptable substitute for the "official" Mazda stuff and works fine. 200k miles on mine with it, so... yep. Meets the specs, works great.

 

[tickerguy]

I've noted no material difference over its service life; I do change MTX fluid on 50k intervals, more or less, but the improvement when I put it in over stock was immediate and I haven't noted any degradation over time, nor do I note a difference when I change it either.

YMMV but that's my experience in the "6".