Engine/Transmission (1998.5 - 2002) NV4500 Lube - I know, old subject but...

[Ncostello]

Just researching a little more on this today I found this excerpt from AllPar... which sounds pretty straight forward compared to much of the reading I've done over the years. Seems like when I did my NV4500 lube change a few years back I used Amsoil 75W90 Series 2000 (or maybe 3000). I do know it was blue. I'm going to change the lube in the 99 3500 at work and was looking at using Amsoil MTG 75W90... or Royal Purple MaxGear 75W85.

So, the NV4500 is a given; use any high quality 75W85 GL-4 Synthetic Gear Oil. Items such as Mobil 1 Synthetic, Castrol Syntorq, or Valvoline Synpower will all do the job nicely. But be warned, the spec is for GL-4 lubricant, NOT the commonly available GL-5 that we've all been using in our front and rear axles these past few years.

API (American Petroleum Institute Classification) GL-4 (Gear Lubricant-4) contains about half the additives of GL-5. Higher concentration of Extreme Pressure additives in GL-5 gear oils may cause the softer metals, such as copper, brass and bronze – which make up the shift synchronizers of a manual transmission - to suffer premature wear / failure. So, stick with the specified GL-4 classification, in any of your favorite synthetic brands.

 

[Joseph Donnelly]

I have used Torco RTF (racing transmission fluid) for about ten years and although rated GL6 it has not attacked the soft metal components such as synchronizer rings. Torco told me their formulation does not cause this problem, and both Standard Transmission (Richard Poels) and I inspected the parts in my NV5600 (Issue 67, p. 84) and found no erosion of the soft metal parts. Keeping the NV4500 cool was one of the reasons for New Venture selecting Castrol Syntorq. I found Torco RTF to be the best other lube to do this of ones I tested, and also to give low HP drag on coast-down dyno testing (Issue 62, p. 21).

 

[Ncostello]

From some other readings (probably seen by anyone researching this topic) it seemed the critical temperature to pay attention to was that of the oil between the teeth in shear. From what I gathered this could be significantly different (much higher) than the overall oil temperature... for that split second. Which eventually leads to all of the oil being overheated at some point if it can't handle such temps well. That temperature is very difficult to detect and probably only by people at New Venture... not me with a gauge in the sump. Thus the choice to use the Syntorq.



I was unable to find any data/availability on the synthetic Valvoline or Mobil lubes with a GL4 rating, as mentioned above.



I will check into the Torco. Thanks!

 

[BBeckmann]

I've had problems with syncros using royal purple so i wouldn't recomend it. Had to replace 3rd and 4th gear syncros and went back to the factory mopar fluid and had no issues. Now swapping in a 6 speed