I want to order some lubricant for My gm nv4500, I read about this and turns out there is quite a bit of disagreement on this matter. Apparently it is bc some say the nv4500 have carbon fiber syncross and some disagree also some say when they are rebuilt the rebuilder will use brass syncross therefore no need for the one and only Castrol Syntorque lube. Some people claim penzoil syncromesh is the proper oil to use, some swear by the redline MT 90. I would rather not risk the tranny since I'm not looking to rebuild it any time soon. I read some saying that the amsoil stuff is even better than the Castrol Syntorque lube so, I know we have amsoil dealers here and many are well experienced mechanics so I'd like to hear Your opinion if You want to share it. Thank You.