Baumst, I never used the Lucas product.I'd be inclined to just stay with standard 80/90 wt gear oil,unless I was starting from scratch with a rebuild.At any rate,it won't heal any noises/problems.

Also,can't say how much the diff will take.I buy a gallon with a pump,and pump slowly till it comes out the fill plug,seal it back up and good to go.It's usually cheaper for a gallon,and I can also use it in the tranny.