I was checking out something for a Balljoint Job on my 98 12v and my buddy said check this out. It was Royal Purple product called MAX GEAR that says its not harmful to soft metals or composites and exceeds recommendations for GL-4 and GL-5. Anybody thought about this for the NV4500 since the Castrol product is pretty hard to get. I have been told there is also Amsoil but you have to order it from a rep retailer so I was curious about this option and its claimed superiority.
Automotive - Royal Purple

 

I'd run the Castrol

 

I have run the RP in diffs and its great .... I reccomend the Red line oil .... over all ..

 

In the NV4500 you wanna run the syntorque

 

that's great but I cant find it anywhere. and Castrol all the parts places get a confused look on their face and Castrol only has it available in drum size High gear a trans reman company in my town I talked to their techs and they said the oem and aftermarket carbon fiber and bronze components are no longer used in either OEM nor their reman components. would love to run the syntorque but DAMMIT why does it have to be such a mystery to find it.

 

Apparently Castrol is no longer making Syntorq LT. Can't say I'm really surprised. It turned out being a boutique oil requirement in a mainstream application that saw excessive failures for various reasons over the years. Often using the wrong oil in the NV4500 simply contributed to the effect of a Cummins driving the shyt out of a crappy transmission. Oh well. I've been using it in my Gear Vendor. Glad I bough an extra couple jugs last time.

Found the GM part# equivalent on Amazon (12346190). Better grab it while it lasts...

 

I picked up the Castrol at NAPA but that was a couple of years ago

 

I used to get it from Quad4x4 and the last I bought from them was also probably at least 2 years ago. They now have a message up on their site saying it is no longer available because Castrol is no longer making it.

I can use other substitutes in my GV, but I'd advise anyone running an NV4500, especially if they are hauling with it, to scrounge up whatever stocks of Syntorq LT might still be out there.

 

Amsoil or Red Line...both are good.

 

Anyone ever use this stuff?

Gorilla Juice Manual Transmission Fluid Case 10 Quart Jug

What line of Amsoil or Red Line are you guys using?

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Sorry for post whoring... From TDR: Ram NV4500 Specifications

"Other Lube Oils for the NV4500

Joe Donnelly tested several brands of oil for the NV4500 and reported the results in TDR issue #??. He also posted tothe TDR Roundtable "The Castrol was best, flat out. Torco RTF was very close, and has the GL6 additive rating for those worried about gear wear. If the lube doesn't get hot, it is easier on the brass synchros. The Castrol and Torco were slow to heat up. It took several full power passes on the dyno to get them to 140 deg. Another popular lube came up to temperature with just one pass. That suggests to me that friction was higher with it, and its higher drag figures (taken in neutral gear, coasting down from 110 mph) supported that guess. However, to get another kind of answer I asked the possibly most learned pertroleum/lubricant engineer (degrees, certifications, etc.), Kevin Dinwiddie. He told me to use Castrol. He sells LE and could have recommended their LE607 (90 wt) or LE606 (80 wt?). Since he took his company out of the controversy, and therefore "doesn't have a dog in this fight" I felt his advice was well meant, and not self serving in any way."

The NV-4500 calls for an GL-4 oil. A GL-4 oil has about 1/2 the sulfur/phoshphorus anti wear additive as a GL-5 does. The LE 607 is a GL-5. NV Gear is asking for a lesser amount of sulfur/phoshphorus becasue of the possibility of the sulfur attacking the light metals in the transmission. Because yellow metals are primarily attacked at high temperatures, systhetic GL-5 oils may not pose a problem due to their lower operating temperatures. Many are using synthetic alternatives to the recommended Castrol oil, whether or not you should is a decision that you should based on your own research.

RedLine MT-90 GL-4 75-90 - recommended by some TDR members who claim it works well.

LE 607 SAE 90 has been used in this application for many years with no problems at all because of the buffer package that they use in the 607 product. It basicly keeps the sulfer in check and does not have an effect on the light metals. This is a quote from the back of the Technical Data Bulletin of the 607 "Use in differentials and transmissons (except those requiring non-ep pur mineral oil) in over-the-road and stop-n-go fleets and off highway equipment. Use in all heavily-loaded industrial enclosed gears. Especially appropriate for heavy donstruction equipment and farm machinery where service is severe. Should be used where drain periods may be longer than normal due to equipment being away from home terminals or difficult access. For use in worm gearboxes and in gearboxes that have bronze gears and thrust washers which require extreme pressure gear oil. Especially appropriate for bowl mills, pellet mills, rock and coal crushers, machine tool gearboxes, gear heads, soy bean oil extractors and other industrial applications.

Amsoil Series 2000 75W-90 - Many have reported success with with this oil. A few have reported that shifting was more difficult, most report improvements in the shifting."