the front tranny seal on my 240Z is lasting about one to two races before it starts to leak. (more than the ocassional drip) The shaft is smooth where it contacts the seal, no burrs or grooves. (I am using a Nissan dealer seal for the repairs) I have added and extra vent on the tranny, in case I was building up too much pressure. I am running Redline MTL, so I don't think that's the case. shaft run-out is withing specs and I use a new pilot roller bearing at each change out. I have replaced the seal 3 times and a Nissan Master Tech has replaced it twice, in the last year. In the previous four years, I never had a problem with the seal. any ideas?