redline mtl vs. mt90

Ive been running mt90 in my ax15 for years now and its due for a fluid change i know mtl is a lighter viscosity but how does it stack up againts mt90?Would i see any inprovement in shifting using mtl?Is mtl yellow metal safe like the mt90?

I picked MT-90 over the other for some reason 5 years ago, and stayed with it, works great. IIRC, the only difference was viscosity.

Im wondering if the mtl might offer any better shifting with the lighter viscosity...is it safe to run in the AX15?