Will soon drain and refill my Diff. I believe that as a canadian "Sovereign", it should have a LSD. Can I refill using any name brand 75-90W synthetic gear oil? They all seem to be Synthetic now. Any possible sear incompatabilities?

 

As long as it is the LSD version of the diff oil, from a decent supplier, it will be fine.

 

As long as it has the friction modifier for the limited slip, it will be fine. A 75 or 80W-90 from a major oil company (Shell/Mobil/ Esso etc) is best. Avoid the third party blenders like Redline Amsoil Etc, they are a waste of money.