I recently had some issues with my NV5600 and I had to open the top to add more oil (see my other NV5600 thread).

While there I started the truck and looked inside, gears in neutral were splashing oil everywhere but not much on top, still it was greasy.

This transmission had Amsoil Syncromesh overfilled by 2 quarts, but lost a some of it (seal leaking a little).

While driving I had this thought that maybe the overfilling wasn't a good idea. The oil is splashed around the case by the gears, if you overfill the transmission there will be no more "splashing", since gears will be immersed partially and won't splatter oil as if they were just touching the fluid.

Are my thoughts correct or just theoretical ? I think this is something to consider.

 

some say to but there was a test with a temp gage that showed overfilling caused it to over heat as well.

 

i used to run it over by 1qt it never got over 200 when towing but in my 4500 i run 2 because it would run lower when going up hill

 

I had mine overfilled a quart also when i had my clutch install, but when i asked the mechanic to do it he gave me this weird laugh and shook his head. From what i heard he does this to all the nv5600s he works on now.

 

Also overfilling mine by one quart.

As for the temp increase from overfilling. Most likely it's due to some very hot parts is getting bathed in oil now which wasn't before.

MikeyB

 

I don't over fill ,and if shifts fine. If you don't abuse your syncros this trans. should for many miles. My NV4500 in my GM has 495K on it with only one input bearing going bad at around 200K. It's all in how you shift it.

 

I actaully had a talk with the rebuilder which is a large dist for many transmissions. The started 1 quart overfill is recommended, and also if towing heavy to add any cooling aid to the transmission. There are some aluminum coolers that bolt on to the PTO covers that will use 1qt more of oil and will drop temperature considerably, they suggest to install also a temp gauge, if oil reaches 270/280 deg to pull over and let it cool off for a while.

Also towing in 6th (overdrive) is not suggested, which is a huge problem with me since I have 4:10 rearend and 5th gear towing means 55mph max, a little slow for interstate travel (I become a rolling roadblock).

They will warranty it ONLY is used with Syncromesh Chrysler or GM oils.

 

I run 2 extra quarts in my NV4500, mostly due to the Fast Coolers (finned aluminum that go where the PTO covers are like Valv mentioned). I have a sender in it as well and never have gotten over 200* pulling a 12K toy hauler up and down the Rocky mountains here in S. Idaho. This is with Amsoil Manual Transmission and Transaxle (recommended for the NV4500) in it.

 

I don't know how you can overfill the NV5600 so much? It's suppose to take 4.5 quarts correct? I know when I changed mine it only just under 5 before it started coming out the fill cap. I can't see any issues with overfilling it as long as you don't go crazy.

 

I have heard of guys saying to overfill their transmission looking to cool it off. Although, in school, I was told not too due to the gears creating foam and thus causing cavitation that leads to parts failure as the gears mesh (Those that know what a gear wine sounds like). More lube in transmission means transmission has to work that much harder when the gears mesh and displace that extra lube, which in turns slows down the vehicle. Ever tried to shift a frozen transmission in -40 weather and you will know how hard it is to move that vehicle until it warms up. You can also lose some of your engines horsepower and torque trying to move the gears through the fluid and end up paying for it at the pump.

Lets also not forget that you have to have room for thermal expansion. Otherwise you will loose your seals. Once you loose your seals you allow dirt to enter and not to mention all that money you wasted in putting that extra lube in, is now laying on the ground. I could see overfilling using an aftermarket cooler on the PTO, but just leaving the transmission stock is just asking for trouble from my view.

Shawn

 

Fill throught the top PTO cover bolt hole.

Most of the gears are already running submerged in oil, so foaming isn't an issue like it would be in a crankcase with the crankshaft 'slapping' the oil if over filled.

MikeyB

 

Consider a one quart ovefill as reasonable protection. Manufactures located the fill hole for a reason. Where their engineers felt it needed to be as a compromise. Two quarts might be pushing the point too far. JMHO

 

I will go with catdiesel-762 If dodge wants to say you need more then go with DODGE. IF not do as the book says save your seals!

 

My transmission is not Dodge issue anymore, if rebuilder (which is DC authorized) says overfill I will do it, here's tag that goes with transmission:



Besides our synthetic transmission oils are not the old thick 80/90w . Even at subzero temps they keep better viscosity than the old type when hot.

I actually installed the oil coolers and it will add another 1.5 quarts for a total of 9 quarts.

They also sell the oil at $ 13/quart which beats DC at $ 22/quart

And finally the NV5600 was plagued by failures from the begin from a later discovered fill hole placed too low, thus not allowing correct amount of oil in the case. An overfill of 1 quart is strongly suggested for longevity of the transmission.

 

Valv,

That's pretty much what the hotshot runners and transmission builders have been telling us for years with the NV5600.

MikeyB