I have a tail shaft seal leaking, so when i change that out i want to go to a full synthetic fluid.. i already run Valvoline full syn. in the frnt and rear diffs. looking for suggestions for a fluid and what type to use and how much.. thanks... i'm in MT where temps drop to -30 sometimes... thanks for any info...

Capn

 

Castrol Syntorq is the only oil to use. Only oil made for the NV4500. Get it at a Dodge or Chevy dealer. $18-$28 per qt and takes 4. Its a lifetime fluid, change it when you rebuild the trans.

 

amsoil sells also been using it for 25k so far so good..made only for nv4500's only $10.00 per quart.....

 

Amsoil says its OK to use but NV4500 doesn't!

 

I didn't know NV4500 could talk!?!?

You need a GL4 oil for the 4500. Castrol Syntorq is one of them, Amsoil has one as well (MTG I believe is the one). The Castrol oil is a full synthetic oil, so unless you can get Amsoil cheaper and easier.

 

I have been running royal purple in my nv4500 and t case for 2 years, Castrol syntorque is the only oil that dodge will warranty, I have heard great things about shafers oil. I have also heard of people using other oils and burning up your bearings, or hard syncro shifting. ask your local transmission shop.

 

I've also been advised by my local gearbox specialists to overfill the case slightly, their advise was to fill to the lowest bolt hole on the PTO cover instead of the normal drain plug. Apparently the front bearings on the upper gear set tend to starve when going uphill if you fill it normally. Takes about 3/4ths of a quart extra . . .

 

The stock Mopar stuff which obviously as stated above is already a full Syn fluid. But at 20-25 dollars a bottle......
Ask yourself a couple questions, can I rebuild my NV4500 if/when it goes? Do I have the money to pay a shop to rebuild it if goes? Do I want to risk burning up the trans with a fluid other then the manufacturer specified fluid?

My, I would probably get the Amsoil, and be happy.

BustedWrench, On the older Getrag 5speeds it is almost mandatory to overfill it by 1 quart. On the NV4500's not too many people have said much about this. I kind of wonder about it myself. I wonder if it would extend the syncro life?

 

If I'm not mistaken.. isn't the "lowest bot hole on the PTO cover" what you take out to DRAIN the gearbox? I remove the cover, clean out the gearbox and service to the correct level with the Amsoil recommended fluid. You must clean the gearbox out well. As for the syntorque being a "lifetime fluid", mine was hard to shift at about 40,000 miles. I intend to change the fluid at 30,000 mile intervals, it's cheap insurance.

 

I agree!!

 

I agree as well about the 30k-40k change intravel. And yes im pretty sure the PTO cover is what you use to drain the fluid so I would just fill it to that level ha. The fill hole is much higher on the housing. I have also heard of people somehow filling the gearbox form the top via removign the shift boot and I guess a few other things. Ive tried it. His argument was that at 28$ a quart he couldt afford to spill any and the OEM fiill hole is a bit hard to get a funnel into.

 

Amsoil has a nifty pump that just screws onto the quart bottles, it's great for hard to get at fill holes. I now have three of them to avoid cleaning the different oils each time.

 

Take it for what its worth, I've used Amsoil and Castrol in my 4500s, the Castrol shifts better and less wear. I've also tried 4 and 5 qt. fills and the 4 qt
fill shifts the best.
If you pour some of each out you can easily see a differance, the Amsoil is a lot thinner, it takes longer for the syncros to slow down to shift easy.

Dealer cost is $18 for the Castrol and is the only oil recomended for the NV4500. It also is LT, Low Temp, made to draw heat from the nv cast iron case.

Quad 4x4
What lubricant should I use and were can I get it?
Castrol Syntorq LTŪ 75w85w GL-4 rated, low temperature, synthetic gear lubricant is the only factory approved lubricant for NV4500 series transmissions. Some other lubricant manufacturers such as Amsoil may have products that are compatible. However, we have yet to see any other lubricant match the specifications of Syntorq LTŪ.

Castrol Syntorq LTŪ is available in quart bottles from Dodge dealers (p/n 4874459) and GM dealers (p/n 12346190). Castrol distributors offer factory sealed 16 gallon drums, plus some repackage the oil in 5 gallon pails. We sell Syntorq LTŪ in two quart jugs.

 

They did a dyno test many years ago in the TDR magazine on the NV4500 and different oils and the Dealer grade oil performed the best for temperature control (read friction, cooling and engagment). They also stated that overfilling the NV4500 was not recommended as it increases hydraulic pressure on the lower shafts and could cause shifting issues.

I replaced my NV4500 from a local gear shop for $1600 with all the upgrades and they also suggested only the Castrol Syntorq oil.

 

Great info! I think thats what we all needed to hear. Think I will be stickin with the Syntorq now.

And yes you can fill the tranny via the shift tower. I did it on my buddys truck, it takes a while, but it works. Remove the shift boot to expose the shifter base, and start pooring very slowly. I had to heat up the fluid to make it go faster. I think it took half an hour for 4 quarts?
That reminds me, I need to check mine while I got it in the shop...