That's some seriously good information there, Jay see! Why don't you give the engine flush a go? What you're trying to do, is dissolve the buildup of varnish on the steel LSD clutch plates. Just changing the oil probably aint gunna do it IMHO.
I reckon this thread should be pinned. What do you think?
I found this youtube clip explaining how LSD (the type used in the Patrol) works: https://youtu.be/WeLm7wHvdxQ