[CarJunkie]

Interesting update, and new question:

I had a track day yesterday. I wanted to be certain that there was adequate fluid in the rear differential, and I'm approaching 60,000 miles so I went ahead and replaced both the transmission and the rear differential fluid last week. I was surprised that oil came out of the fill plug, meaning at the rear differential was not low on fluid at all. After filling it back up, I cleaned a small section of the axle hub immediately adjacent to the differential output so that I could see how much oil or wetness accumulated during my track day.

This morning, I was surprised to find that the small section I had cleaned remained completely spotless, no oil on it at all. The adjacent CV boot is also in excellent condition and doesn't show any moisture on it.

I see two options. First, maybe the oil that got onto the driver side axle hub where it joins the rear differential output came from something else, not even my car. That doesn't seem possible. The second option is that my previous fluid was old, differential got too hot, and some vapor managed to escape the seal, but with fresh fluid in there, no leakage is occurring. That would suggest that the driver side output seal is nearing the end of it's life, but there is no rush to rebuild. The LSD itself still seems to be functioning as it should. Thoughts?

I may not need to rebuild the diff this season after all, and it wasn't exactly in the budget. I have at least one more track day planned. I have now completely cleaned the entire axle hub and driver side of the differential, and will monitor it after each track day until I see fluid there again.