I will Agree with Molakule, I have moly additive in my tranny. 4th gear syncro is missing it if I shift quick. Same story with my Fathers truck, but 1st gear. It started doing it after couple month. First he said it shifts better than ever, he got that truck brand new, then 1st gear syncro started acting weird,and again only if you shift quick. My tranny wasn't perfect since I got this car, so I wasn't sure. My Dad's truck--may blame it on moly, maybe age and mileage. It is 06 Frontier with close to 100k miles, same gear oil and same additive as in my sig. Don't think I'll drain it soon, since it is synthetic and not cheap, but won't add MoS2 for gears there next time, for sure. It will probably do a good job in differential.