M931 engine/trans oil

[D6c]

I'm sure any good 15/40 diesel oil is OK for the engine but does the trans oil have any special requirements that not all 15-40 engine oils will meet?

(I usually stock Case-IH engine oil for my other equipment)

 

[98G]

Edit to add picture - I've used this stuff with no I'll effects

 

[MuleMac01]

you need to use a trans fluid that has a Allison c-4 rating... most of the time it will say on the outside on the item.

 

[D6c]

The TM lists "OE/HDO 15/40" for both the trans & engine unless used in very cold weather and then Dextron III is recommended. Don't have any idea what oil would be an equivalent to the OE/HDO.

Since I don't know what's currently in the trans, if it gets low I probably should do a complete change so I'm not mixing oils.....just difficult to know what to change it to.
One source I read listed the Allison C4 rating as obsolete, but that's probably for the new trasmissions currently being built.

 

[Csm Davis]

Show me where the transmission is supposed to be using 15/40w.

 

[98G]

Lube order calls for straight 10 weight..

 

[6x6guy]

Talked to a couple of guys at Sparta vehicle maintenance facility and they said -same motor oil in the engine and trans 15-40 unless its extremely cold then they use 10 w. Checked with the guys who did it for a living and worked on these trucks ( right from the source ). Did all of my trucks that way.

 

[elkhtr]

I have seen two different revisions of the 939 lube order. One calling for 10w, one 15/40. I put in the 15/40 when I did the engine swap in my 923-a1. The trans appears to like it just fine, shifts smooth, etc.

 

[Swamp Donkey]

Show me where the transmission is supposed to be using 15/40w.

From the -10 Operators Manual...

 

[Swamp Donkey]

The first one I posted is from the revised manual. This is from the original manual.

 

[Csm Davis]

Okay I was wondering where all these people were coming up with 15/40 versus 10wt now I know thanks Swamp Donkey but the original manual called for 10wt.
Check the dates on and in the first few pages for which manual is newest and has what changes, back in the day I was a technical publications librarian for awhile. The original TM'S for the 939s I believe we're dated 1984.

 

[Swamp Donkey]

Thanks Jeff. The charts above are from the two versions available for download on SS if that helps. I need to find that 1984 version since that would be original to my truck, being it's an M923 (A0 *snicker*).

 

[patracy]

From what I've been informed, the military decided to move to 15w40 as a cost savings measure. Instead of having to supply the M939 series trucks with engine and transmission oil, they could use 15w40.

That said, I'm running 10wt transmission oil. (Boy have I gone through enough of it!) My pockets aren't as deep as Uncle Sam. It's cheaper on a fleet scale to use a single oil and bear the fault of possibly less service life.

Also note, in the TM's there's mention of acceptable fluids in the transmission. Cooking oil, fuel, and even water were mentioned as get bys. Again, yeah, it might work and get you out of a jam. But I'm not having to drive my truck out of a war zone.

 

[Csm Davis]

The new TM still list 10wt but only for 55°F down to -4°F, 15/40 from 10°F - 110°F, Dexatron 3 from -15°F- 75°F, and OEA from -65°F- 40°F think it might be learned from more operations in hot climates.

 

[D6c]

The manual I have has a last change date of 30 Sept, 2004 (TM 9-2320-272-10)....I downloaded it direct from the logsa.army.mil site a while back.It seems to support the idea that they've gone to a single oil for engine & trans as it lists 15-40 for trans except for very cold operation.Still not sure if the Case-IH 15-40 I have meets the spec. I lists an API CI-4, CH-4 & SL .....Is the CI-4 same as C-4?Nothing like having a system of confusing oil specs....

 

[D6c]

Found this page: It seems to indicate that OE/HDO is equivilent to API CI-4http://www.uslube.com/SPEC SHEETS/Mil Spec H.pdf