Torsen Lifespan?
 

Looking to replace my worn out Torsen, is there a an upper limit to milage I should look for when shopping used diffs? Or is hard use more of a factor than overall milage and age?

I was always under the impression that torsens didn't wear out, but could be wrong. I did have one start acting kind of weird on me, but it certainly could have been fluid/abuse issues.

For a couple datapoints, both cars lived most of their turbo life in the low 300hps:

I bought a '99 at 100k miles, turbo'd it and put another 50k on it. It still worked fine in general, but toward the end of it's life occasionally it seemed like it would want to not lock up when it should have (making a turn from a stop in the rain one tire would spin for a second before locking) or lock when it shouldn't (driving through a parking lot it'd sometimes skip the outside tire for a second like a welded diff would do).

I bought a '00 at 160k miles, turbo'd it and put another 10k on it. It drives great, very seamless. Locks up when it should, opens when it should, no issues with it at all, just under 170k miles.

That's what I thought to, but I've got 75-100hrs of track use on mine and it's wheelspin city. There's some spec miata voodoo out there on rebuilding them, just looking for a more economical option.

I think as long as you get one that wasn't tracked it will probably last you another 75-100 hours. just a guess.

How often should the gear oil be changed in a torsen?