Are you sure it is a Torsen and not a Spider?

My old OFNA 9-5 had a Torsen. It had a dust cover, but was not sealed. It used gear grease that was specially designed for this application.

One of my Hypers has a Spider (which has an extra couple of gears - compared to the standard diffs). On this, I use 5000 wt silicon fluid.

What ever you have, clean it and relube it with the proper material. The "feel" should be more or less the same as your other diffs.

Hope this helps.