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I'm running a '96 Dodge NV4500 behind my 4BT. I'm a little confused on the internals of this tranny. Several references I've seen say it has Carbon Fiber synchros. Other tranny/gear repair & parts shops on the net refer to the synchros as being the more common brass type.

Some sites explain the need for the $pecial NV4500 lubricant being that anything else can dissolve the C/F snchros. Maybe it's just me, but I can't see how carbon fiber is able to hold up in this extreme stress application for synchros. Even brass takes a beating over the years, and the NP 435's aluminum synchros take some noteable wear.

The two reasons for this post: are NV4500 synchros C/F, or brass? Is the reason for the lube spec because of synchros, or because of seal/lube compatability? I used a Valvoline synthetic lube and have some weeping at my rear seal....
 

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First off, why would you even want to take a chance and install the wrong lube?? Run what is recomended from the dealer. And the blocking rings are made from brass, but I think they are still the reason the factory wants the special lube.
 

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I know many on different forums claim they are using many different lubes in thier NV-4500's........good for them. I will 'only' use the recomended lube available from GM or Dodge. Its expensive, but my NV-4500 is a lot more expensive to destroy using the wrong lube. The NV-4500 design requires this special Lube.

Paul
 

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Factory NV4500 syncros are carbon fiber composite, maybe some cheap aftermarket ones are brass but not the originals. Use only the recommened lube or your tranny will suffer premature wear. Dan at www.Quad4x4.com knows his stuff when it comes to NV4500's.
 

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there is a very extensive writeup of different lubes and specifically their breakdown quality and I believe the condition of the synchros... Conclusion is, even though there are even some very good comparable sythetics, hands down the best is the factory Castrol Syntorq lube.. By far cheapest place to get it is from a GM dealer, $16 a quart if not that low then talk them down as they can offer that price. Second best place is standard transmission in TExas, they sell it in milk jugs that they fill out of 55 gallon drums they have. I personally would never run anything different than the factory fluid in a 4500.. Also, I believe they are carbon fiber/kevlar?
 

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The blocking rings in a GM NV4500 (never worked on a Dodge, but I can't think they would be different) are a brass outer ring lined with friction material of some kind. Whether it's carbon fiber or not I don't know, but back when I was a GM tech, I replaced the blocking rings in more than several 4500's because of the owner going cheap on the lube. The friction material would be completely gone, leaving only the brass outer. Pay now or pay later.

I am a believer in synthetic gear lube. I started using it in the quickchange rear end in my racecar several years ago. After 25 laps of racing, the spur gears are warm, but not so much so that they can't be handled with bare hands. With conventional gear lube, you'd better use gloves. That reduction in operating temp just has to be beneficial in terms of longevity. I don't know if the 4500 lube would be the best choice for the 205, but I would highly recommend a synthetic lube of some kind.
 

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I installed a NV4500 - NP205 combination in my 91 Dodge and have been running Castrol Syntorq in both for the last two years without any problems.
 

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Discussion Starter #10
Thanks, guys. I'll drain and change. I think I found it for $10 quart in 2 quart bottles, AFTER I used the other, but will really have to search for the guys link!

As to the question, "First off, why would you even want to take a chance and install the wrong lube??" the answer is cash flow at the time. If you don't have it you can't spend it, ya'know?

Thanks, all!
 

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If you go with Castrol make sure it is SYNTORQ and NOT SYNTECH motor oil. This has been confused in the past.
 
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