NV5600 fluid change complete...have question...

[DGibbs]

Just finished the rear differential and NV5600 fluid change. I searched the subject and read multiple threads beforehand, so off I go. Everything goes as planned but when filling back up the transmission, it only takes approximately 4 quarts to fill it back up, and that's with some overrunning back into the drain pan. I was expecting at least 4 1/2 - 4 3/4.



I removed the PTO drain bolt on the driver's side to drain the fluid. Let it drain for at least 20 minutes and put the bolt back in. Thought for sure it would all be out. Now I'm wondering if I should have removed the lower bolt on the passenger side... thoughts?

 

[Gary - K7GLD]

4 quarts is all mine will take - and THAT'S forcing it...

 

[amsoilman]

Just finished the rear differential and NV5600 fluid change. I searched the subject and read multiple threads beforehand, so off I go. Everything goes as planned but when filling back up the transmission, it only takes approximately 4 quarts to fill it back up, and that's with some overrunning back into the drain pan. I was expecting at least 4 1/2 - 4 3/4.



I removed the PTO drain bolt on the driver's side to drain the fluid. Let it drain for at least 20 minutes and put the bolt back in. Thought for sure it would all be out. Now I'm wondering if I should have removed the lower bolt on the passenger side... thoughts?

I recently changed mine, and this is what it took. Just a little left in the 4th Quart.

 

[MMeier]

Ditto what they just said !!

 

[RGardner]

What lube did you use and at how many miles?

 

[DGibbs]

I've got 33,500 on the clock and I used Penzoil Synchromesh manual transmission fluid. Mobil 1 75w-90 synthetic in the differential.

 

[bzingre]

I installed fast coolers and poured in 8. 5 qts through the top hole on the cooler. Should allow fuild to cover the mainshaft for extra lubrication. I know it helps keep things a little coolers.

 

[Diesel Nut]

I thought I heard someone say to overfill the nv5600 about a quart for better cooling or lubrication or something, I can't remember. Anyone heard for that. I know you HAVE to do that with the old Getrags, but I don't know about the NV5600.

 

[rbattelle]

If you overfill it is there a danger of foaming the oil like with an automatic transmission?



-Ryan

 

[Gary - K7GLD]

If you overfill it is there a danger of foaming the oil like with an automatic transmission?



-Ryan

Can't see where any "normal", smaller degree (like 8 ounces) of lube would cause any problems. I'm unclear as to whether normal lube levels are held below shaft seals or not - and I'd sorta tend to get nervous abour submerging those seals in/under lube lots more than I would lube foaming...

 

[KD7GYJ]

OK,



You've changed the fluid in your transmission. Any difference in the way it shifts?? Does it seem to be smoother, quieter??



Blair



I eventually need to do it within a couple thousand miles, so I'm interested in this thread.

 

[mberry]

Blair, when I changed mine I only had about 2K miles on it. Now I'm at 21K and it's a bit looser now. I did not notice any difference in shifting when I changed the lube at 2K. Could have been too new or ?????

 

[mrsnow]

I changed mine @ 25,000 with the factory fluid and I think I made it worse. It feels real stiff like it was when the truck was new.

 

[amsoilman]

If you overfill it is there a danger of foaming the oil like with an automatic transmission?



-Ryan

Transmission fluids, like engine oils have anti foaming agents in them, so if the fluid foams there is a problem with the fluid... ... ... ... ... it has broken down.



Wayne

amsoilmsn

 

[KD7GYJ]

I changed mine @ 25,000 with the factory fluid and I think I made it worse. It feels real stiff like it was when the truck was new.

I am thinking along the lines of trying the syncromesh fluid everyone is talking about. Got a 50 dollar card in the mail from Dodge. May have them change out the fluid, or have the front differential done. Have about 28K on it in 12 months. Time for a fluid change.



Thanks for the input.



Blair

 

[DGibbs]

OK,



You've changed the fluid in your transmission. Any difference in the way it shifts?? Does it seem to be smoother, quieter??



Blair



I eventually need to do it within a couple thousand miles, so I'm interested in this thread.

I didn't really notice any difference in shifting after the fluid change until this weekend when towing the boat. Seemed to shift smoother with some weight behind it.

 

[puebla]

I have a NV5600. I switched to Synchromesh at 20K, 4 quarts, shifts nice.

 

[Shooter]

I remove both PTO covers and inspect for metal ( visually and with magnet ) in the bottom of transmission case. I use heavy PTO gaskets (. 045 in thick ) to reseal PTO covers, just a skin coat of silicone on both sides of gasket and allowed to dry before reassembly for no stick gasket peel off . Gaskets are about $. 35 each at local big rig transmission rebuild shop.

Easy off, easy clean off and easy back on.



My nv5600 was ( notchy/ synchro bump/ catchy/ etc. ) going into 3rd and 5th when it was below 50*f until engine reaches operating temp. It was like that from day 1. Changed the fluid to Q S at about 4k miles. It did shift smoother when warm but not when cold. Another 30k of towing at 21,600# gross and now it shifts smooth even below zero with no signs of the slight syncro grind it had when new. I will change out the lube again this spring.

At the first change the fluid looked like half mixed gold metallic lacquer. Cant wait to see how much more brass is suspended in the lube this time. It should be broken in by nw so fluid should be remain clearer for future changes.



Diff changes ( factory fill looked like grey clay slurry ) have all been clear and clean when changed at 15k intervals. Royal purple 75-90.



I called AA way back when and they said if it were them, pulling 21k# in the desert at up to 120* ambients they would not do it with 90wt. They said DC put the 75-90 requirement and the 15k changes for warranty only. DC did not want any warranty expenses with the diff. AA said same axle in GM's and GM recommends 75-140 for heave duty . I don't recall the chevy gear lube change interval but it is very very far in excess of 15k mi.