Redline MTL is a good appropriate lube for your NV3550, so is Redline Synchromax which is usually available locally.

However, if you're talking about the noise that a Jeep transmission (AX-5 and AX-15 too) makes at idle when in Neutral and your foot is off the clutch, that is the normal sound of the bearings and shafts spinning inside. There is no soundproofing plus they are truck transmissions so you can hear things like that in a Jeep.

 

Thanks Jerry, I know I can't eliminate the noise I just want to quite it down if possable. I changed the fluid last fall to the pennzoil synchromesh and it did not sound to bad when the temps were cooler, but now thats its summer its pretty quite in the morning but after a 30 minute drive on the hwy in 90-100 degree heat it sounds like a dump truck. It seems like the pennzoil gets too thin.

 

Pennzoil Synchromesh is not the best choice of lubes for the NV3550 anyway. It meets the spec but it wouldn't be my first choice.

 

Thanks Jerry :wavey: