My RX7 has been in storage for the past few years and I'm just getting all the fluids changed up before I start driving it again.

Can I use Royal Purple MaxGear 75w90 in BOTH the diff and transmission? RP says that it is both GL4 and GL5 and non corrosive to soft yellow metals (brass, bronze).

I've read the "Redline vs Royal Purple" and "Redline vs Neo Tranny Fluid" threads, and most people recommend the Neo 75W90 HD for both, but I'm in Canada and shipping across the border is $$$. I've seen people use MaxGear in the diff, and a different fluid in the transmission too.

I see that Royal Purple also sells a Synchromesh for manual transmissions as well. The MaxGear is readily available so that's why I was wondering. I can also get Redline MT90 locally as well. I'm not asking which brand is better vs another, but which product to use exactly where.

Any help would be great, thanks.