Check out this link I found on TDR today. It's an eye opener for sure. You're welcome in advance!!http://www.carbonitecummins.com/Documents/Trans%20Oil%20Comparison.pdf

When I worked at Inland Truck Parts and Service, we had tons of trannys come in with lots of issues related to the wrong lube, On all the NV trannies in Dodge and GM rigs we found that the Pennzoil synchromesh was the best oil but we actually bought it from GM as it was the penzoil product labeled as GM tranny oil but was cheaper than penzoil branded containers believe it or not.Problem was with the synchros and not the main gears or bearings, any oil other than the synchromesh would kill the synchros and cause very hard shifting.I have not had the chance to work on or have anything to do with the newer G56 trannies though. If the synchro material can handle the heavier oil then all is well.

W+F...........I've used Amsoil MTF in my NV5600 since the first fluid change. Change out about every 50,000 mile. Not a single problem; and I tow a lot. Just under 186,000 now.

W+F...........I've used Amsoil MTF in my NV5600 since the first fluid change. Change out about every 50,000 mile. Not a single problem; and I tow a lot. Just under 186,000 now.

I know Amsoil users had good luck with it as well and we would use it if a customer requested it or supplied it but from a service center stand point they couldn't justify the extra cost of putting it in otherwise and the store didn't stock much more than what they used mainly for oil to keep overhead down.

I know Amsoil users had good luck with it as well and we would use it if a customer requested it or supplied it but from a service center stand point they couldn't justify the extra cost of putting it in otherwise and the store didn't stock much more than what they used mainly for oil to keep overhead down.

I'm not an Amsoil proponent by any means.......just ask Michael!!! I hate their marketing. Only reason I use it in my '04.5 is that when I needed to change out the diffs, tranny and transfer case the first time (all which specify synthetic) Amsoil was actually cheaper than OEM fluids and Royal Purple at that time. It's worked just fine, and so I've not pursued other fluids since. I just keep reordering the Amsoil.

I'm not an Amsoil proponent by any means.......just ask Michael!!! I hate their marketing. Only reason I use it in my '04.5 is that when I needed to change out the diffs, tranny and transfer case the first time (all which specify synthetic) Amsoil was actually cheaper than OEM fluids and Royal Purple at that time. It's worked just fine, and so I've not pursued other fluids since. I just keep reordering the Amsoil.

What is the spec on the tranfer case.. ATF?

In researching the MB 235.1 it meets MAN 341ML, as does several other oil choices stateside. One of them is Amsoil MTG 75w-90, but I never see anyone running it. The specs line up closer than the syncromesh, but ???