I did some reading from Mike L @ inglewood transmission ( diesel place), he was saying that the 5w 30 engine oil would perform better in the T case because these things get so hot. I guess the dextron doesn't really handle the heat aswell, which makes sense... engines run hotter. Anybody have any input??? Mike is pretty famous as one heck of a Allison Tranny biulder and i think he may be onto something.

 

With today's high demand T cases, I would agree that the dextron or any conventional oil would not protect near as well as the TranSynd or other synthetic trans oil. They are much more heat stable. If using an oil, would also recommend a synthetic. Here is an article I found by GM on the fluid recommendations and it does mention the use of C4(not CH-4) diesel motor oils. The motor oils are more viscous therefore would produce a little more drag(less efficient). The syn trans fluids are similar to a 0W-20. Most motor oils also use viscosity index improvers which can, over time, can shear down and thin out the oil. The TransSynd and equivalent* do not use VI improvers.
IMO you can't beat the TransSynd or equivalent*.

http://www.allisontransmission.com/documents/product/13-TR-90,%20Rev%20E.pdf
Heath

 

I disagree that TranSynd and Amsoil atf will be enough for the transfer case to fight off heat. As`far as too much drag; I disagree with that also. We used 8 qts of Mobil 1 and 4 qts atf years ago in the AXOD and AXODE Taurus transaxle ( automatic ) to stop geartrain failure with great results. The transfercase is very similar to a stick trans and there will be no noticable drag.

 

Hey Mike, think I recognize the name
It's been a while since I posted this, had to re-read. My response based based on use in the transmission itself, although being referred to as T case.
Ally tranny was mentioned which had me wonder if it was the tranny being referred to????
If he has warranty left and manual calls for ATF, any concerns?

 

Mike , will the 5w30 be ok in the electric shift transfercase aswell??

 

Yes, that's what I am using in my transfer case.

 

Thanks Mike!

 

for what it is worth, i changed mine when i did my s/c. i recently went to cape cod towing 6000# cargo trailer. i need 4wd to back in my driveway which i did before i left to load the trailer. problem is i never took it out. towed all the way except about 30 miles in 4wd doing 75-80mph. call me nuts and i swore myself up and down once i realized it, but unlike with the atf in it i didnot even know it was in 4wd. no noise whatsoever. usually i hear it very loud in the cab, typical 4wd noise. now i have none. i am yet to drop the fluid to see how it is. i will report to you all once i do.

 

I need to get mine switched what oil does everyone like(not talkind to you Heath we all know what you preferr)

 

Stick and stones...:p