Actually, here. If you decide to change out the oil, and the particular Torsen you bought has port widows around the OD of the main body (some brands do some dont), this is what I would do:
Start by picking up two or three cans of Lectramotive spray electrical cleaner. It's as strong a spray solvent as you want to go as far as rubber seals are concerned.
Drain the diff.
Jack the rear end of the car up (jackstands and front wheel choks of course).
Leaving the drain plug out, remove the fill plug (this is assuming the fill port of your diff faces the diff/rear of the car).
Use a light to see if one of the windows in the body of the diff is at least halfway facing you. If not, rotate the drive shaft so the diff turns until one is.
Hose that bitch down with the Lectramotive. If you have a friend/helper, have them turn one wheel while you do so. This will allow the solvent to get in through the tangential gears inside the diff.
Rotate the entire rear end again until the next window lines up with fill port, and repeat.
Continue this for at least once for every window. The more times you do it, the better.
Let the rear end back down, allowing the Lectramotive that has accumulated in the nose of the diff housing to drain, then spray more in again to try and flush that remaining antichatter additive out.
Once that finishes draining, immediately put the drain plug back in, and refill the diff but with conventional non-LSD oil.
Draining that oil and doing a refill after driving, I would recommend.
Costly, yeah, but better than the diff being fucked and not working correctly.