Changed the differential oil last month. Fluid was in great shape, changed it back in 2015. But used some questionable Mobil I oil off Amazon. The 8.00 a quart should have been a flag.
But drain plug was packed with a hard black sludge. Assume it was oil contaminated when metal particles. Never saw metal, and used a screwdriver to scrape out of the hollow in the plug.
Went to my local Advance Auto to source a known legitimate differential lubricant.
Redoing the supercharger oil is also on the list.

 

I use Redline shockproof heavy in all my diffs and manual gearboxes

QLD is a hot climate if I was in a cold climate I'd go with the lighter shock proof range
The heavy made the 6 speed manual in my Renault Megane RS feel like it was set in butter beautiful