I have an early '04 3500 with 6 speed manual and Southbend clutch. I am pretty sure it has the NV5600 in it. Anyway, the gearbox is extremely notchy and sometimes will not go into lower gears, and hard to get in higher gears at times. Has anyone experienced this with their truck? Will switching fluids to Redline MTL or Amzoil help this problem? Is so, which one should I use? Any help would be appreciated, Dave.

 

I just started speed shifting my NV 4500 until it was smooth. Now it shifts faster then heck!

 

changing oil has always helped mine. Pennzoil syncromesh at autozone is the factory fluid

 

I thought Castrol Syntorq was the preferred oil. Maybe that changed for the 5600.

 

Yep, the NV5600 uses a lighter lube, 5w-30.

MikeyB

 

Mine shifts notchy when hitting 3rd, and it can decide it doesn't want to go into 1st or reverse after it's been idling.

Redline MTL helped some, but I've talked to other folks with the NV5600 and I think that some of them just don't shift very easy.

 

I have to go to third or 4th and than back to 1st after idling, I think that is nornal. When I am rowing the gears I just "open palm" the shifter from second to third because the shifter will center in the 3rd/4th gate automatically.

 

Just replaced my fluid w/Syncromesh over the weekend. What came out looked fine, but it does seem a bit smoother coming to work this morning.