ok so my car will grind slightly if i shift fast into 6th gear. Friday i bring the car to infiniti and take a tech for a drive and show him and he says its the 6th gear syncro (like i thought) so they say bring it by monday for inspection. they call me today and say we will need to charge 799 incase its not covered under warranty and now im getting scared because i have jwt clutch and flywheel (which i installed 2k ago) and the grinding has been happening before that and i changed the trans fluid to redline mt-90. They said that an aftermarket clutch can void warranty and if the fluid wasnt changed at 30/60k and if its not oem nissan fluid. I looked in the service manual and it says that its recomended to change at 30/60 but not required! Also i checked and it says that i can use any trans fluid thats 75-90w and gl-4. So now that ive figured this out and im going to b!tch at them but what can i say about the clutch? has anyone dealt with this before. Honestly how would a clutch even affect a 6th gear syncro? i apprecaite the help and ive been searching the forum with out much luck