This weekend I changed the oil in my 05 nv5600. I went with 6qts. Penzoil Syncromesh and 6 ounces of Motorkote. Truck shifts smoother considering it has a dd clutch. Also has less noise from the trans at idle. $.02
I drained it from bottom pto cover bolt and filled it from the top pto cover bolt on drivers side. 6qts plus 6 ounces. Truck was on a level shop floor. No problems.
This weekend I changed the oil in my 05 nv5600. I went with 6qts. Penzoil Syncromesh and 6 ounces of Motorkote. Truck shifts smoother considering it has a dd clutch. Also has less noise from the trans at idle. $.02