I am a little confused as to whether I might have a problem or not. When starting out from a stop, if I make a hard left or right turn and am on the gas pretty good (not spinning the tires, but moving briskly) I feel a little bit of vibration or shudder from the rear of the car....no real noise per say....I used Mobil 1 gear lube, and had the same issues (it has a limited slip additive). The limited slip additive apparently was too slippery for the synchros, and I started getting "crunches" when shifting. So I ditched the Mobil 1 for Redline 75w-90NS which means "no slip" for the limited slip. Shifting is perfect now, but I still get the vibration under the very specifc conditions posted above. I called Redline, and they suggested adding a bit of slip additive (1%) which I did, and this seemed to help a bit, but not completely. I am hesitant to add more, as it might effect the synchros (and why they recommeded not using their standard Redline 75w-90 gear oil which comes with 4% slip additive already in it). Hans has me thinking this is perhaps the "normal" operation if the limited slip locking and unlocking? I'm not familiar with how the thing works, so I am asking you more learned folks out there. Thanks!