I went to Canadian tire and couldnt find anything specifically for Diff's

I did find Motormaster transmition oil. Has anyone used motomaster before?

its full synthetic..

 

I use NEO synthetic. Buy one gallon and you can fill up the tranny and diff...

 

According to Mazda, they can be if you buy GL-5 spec in 75w-90 weight. Neo is a good choice for that approach.

In theory, (since we dissect everything else here), they are different gearboxes with different gearing and therefore different needs. The diff is a hypoid gear, which benefits from maximum lubrication and EP protection. It is a torsen diff, not a clutch-type, so you don't need to buy special limited-slip formulations with friction modifiers. I won't recommend any particular one, but I will say that you want a GL-5 or GL-6 synthetic. This will keep friction and diff temps at a minimum.

The transmission however is a compromise between the protection of the gears and the performance of the synchronizers. The gears almost never have significant wear, so I think synchronizer compatibility is the priority. It's well known that GL-5 oil can make things too slick for the synchros, which is why I personally feel a GL-4 gear oil like Amsoil MTG or Redline MT-90 is the best overall choice.

Dave

 

Anyone know shops in the GTA that carry name brand gear/diff fluid?

i went to Canadian tire, and all there was is motormaster...

Would it be ok to run motormaster in a rx7 ? at the proper GL and weight ...?