Allison commercial truck transmission fluid type??

[Damon]

Okay guys, I haven't been around here much, but I have come across an issue that I know you BITOG experts can help me with...

I have an Oshkosh M977 HEMTT military 8x8 cargo truck. It has a Detroit Diesel 8V92TA engine, and an Allison HT 750 CRD 5 speed automatic transmission. I recently put this transmission in, and was under the impression that it was a fresh depot-level rebuild. I filled it with Dexron 3 atf (Chevron) and drove the truck for about 400 miles over the last few months. I began noticing the transmission slipping in 1st gear very early on. It has now gotten so bad the truck is barely operable, and the fluid is very dark. I have set up an appointment to have the transmission rebuilt at a factory Allison Remanufacturer next month.

My problem is the Allison rps are saying that any fluid that is C-4 approved is okay to run in it. The factory Allison literature bears this out. The military literature specifies that I should only run 15-40 oil in it. I have spoken to several MILITARY techs who state that they ONLY run 15-40 in their hemtt transmissions, and that atf is not able to cope with the high temps that this transmission creates.

I just want to make sure I am filling this tranny with the right stuff. Is 15-40 C-4 certified? What brand is best? I usually run Delo 100 or 400 straight 40 weight in the engine.

 

[MGregoir]

A wide variety of 15W-40 HDEOs meet Allison C-4, including Chevron Delo, Mobil Delvac and Shell Rotella.

Dexron III meets C-4, but I would look at something like Mobiltrans HD in SAE 30.

http://www.mobil.com/USA-English/Lubes/PDS/NAUSE2CVLMOMobiltransHDSeries.asp

It is a straight 30 oil designed for use in Caterpillar and Allison automatic/powershift transmissions, and is rated C-4.

 

[artificialist]

Amsoil makes a variety of products that work where Allison C-4 is required. I'm sure one of the Amsoil experts can help you out.

 

[Dualie]

Allison transynd. Not cheep but its what Allison says is good for the long haul.

 

[Gary Allan]

ATD
https://www.amsoil.com/storefront/atd.aspx
AMSOIL Torque-Drive™ is recommended as a direct replacement for TranSynd® Synthetic ATF in heavy duty, on and off highway automatic transmissions manufactured by Allison,® General Motors,® Ford,® Voith® and ZF® or wherever the standards TES-295, C-4, Dexron® III, Mercon,® Voith G-1363 or TE-ML 14C are specified. Examples of operations that benefit from using AMSOIL Torque-Drive™ include municipal or transit buses, motor coaches, garbage haulers, motor homes, delivery vans, emergency vehicles, school buses, dump trucks, utility vehicles, cement trucks, line haul trucks and tow trucks.

 

[Damon]

Thanks guys, but I want to stick with a motor oil that meets allison's specs so I can also be following the military's requirement.

I'm not a big fan of Amsoil anymore, and I sure don't think $1000 for 30 gallons of fluid is reasonable. I wonder how much the Allison Transynd fluid costs....

 

[onion]

Allison Transynd will be even more expensive than the Amsoil product... but at least it's licensed for the TES-295 spec (i.e. proven to meet the spec- unlike Amsoil's 'reverse engineered' offering).

I just did an engine swap in a HEMTT, and its transmission was filled with 15W40. I work at a Detroit/Allison shop, in the engine department. I rarely work on the transmissions, so any info I give you is second-hand... but I do know that lots of the larger Allison transmissions are routinely filled with either 15w40 or DexIII depending on application and customer preference. These transmissions are reputed to "run cooler" with 15W40, though I'm not speaking from direct experience here... this is just what the transmission guys tell me.

Just out of curiosity- what are you using a monstrosity like that for?

 

[Damon]

Originally Posted By: onion
Just out of curiosity- what are you using a monstrosity like that for?


Thanks for the reassurance. I definitely thnk now that 15-40 is the way to go. It's just a question of which one. Delo 400 good?

My hemtt is a complete frame-off restoration I did over the last two years. All I do is drive it around town a couple times a month and enjoy it. It's a hobby. Never had anything on the bed of it, and don't plan to. I do use the telescoping-boom crane a bit though for fun. I'd post a pic but I don't think you can do that on this forum.

 

[onion]

If you'll click the "switch to full reply screen" button at the bottom of this page, it'll allow you to post a hosted image. Here's a picture of a HEMTT so folks will know what we're talking about.

The one that I swapped the engine in was an Air Force firetruck on a HEMTT chassis. We had just had an ice storm on the morning that I got it running, and I took it out for a test drive. It was fun making that 450hp, 50,000 pound monstrosity slide sideways. I tried donuts but couldn't do it... maybe if I'd had more room.

 

[Damon]

Oh, thanks for that. Here's a pic, and a link to a website called Steelsoldiers that I have used to document my restoration of this truck. I think you have to register to see the pics, but it tells the whole story of my work with this particular truck.


http://www.steelsoldiers.com/showthread.php?t=16105&highlight=hemtt

shoot, I don't have any pics hosted.... Go to the steel soldiers website in the link and sign in to see a ton of them. Mine looks like brand new now.

 

[onion]

I think that any 15w40 that meets the C-4 spec should work fine. I did a quick google, and Delo400 meets the spec, as does Delvac 1300... probably lots of 15w40's do. Personally, I don't have any preference other than that you should stick with a trusted brand. We use Delvac at the shop.

 

[onion]

Looks like I misread that Delo site. Turns out that Delo 15w40 does not meet the Allison C-4 spec. But Delvac 15w40 does.

 

[Damon]

Okay, now I am hearing from Allison that they are no longer recommending C4 fluids, and I should be using a C3 approved transmission fluid.

Can anyone recommend a C3 15-40 oil?

 

[MolaKule]

I would think the Amsoil Torque-Drive™ ATD https://www.amsoil.com/storefront/atd.aspx should work for the Allison C4 unless this is a modified tranny requiring a higher viscosity fluid. The Torque-Drive™ is a synthetic which would take the heat better than a mineral oil HDEO.

Thge only alternative might be the Mobil 1 Delvac Synthetic.