M923a1 transmission fluid?

[Andydieselpower]

I have the M939 tech manuals coming and will be posting them to our site soon. In the meantime what do these trucks have for trans fluid in the Allison 654's from the military? 10wt? Do any of you M939 owners here change yours over to Dexron?



Thanks,
Andy

 

[PowerstrokeNC]

I have the same question.

 

[midcounty]

Curious of this one myself, as I am thinking of a 923 in the future.

 

[PowerstrokeNC]

Is there any reason to switch?

 

[Nonotagain]

Is there any reason to switch?

My best educated guess would be longer service life if you change over to Dextron.
ATF has better heat transfer properties than engine oil, plus most ATF contains friction modifiers which engine oil doesn't.

 

[73m819]

Others have said that motor oil in the trans is a mil thing because of a ease of supply , that ALLISON calls for the DEXRON, there is a thread about this on site, think it says dex 3

 

[Jersey4x4]

As a shop the works on heavy equipment I can say for sure that Dexron is the way to go. The military used 15w40 eng oil in the trans because that was a common fluid but it had an issue of shellacking the clutches. This was a major problem in the M35A3 and I am sure the other trucks as well. I would change to Dex and be done with it.

 

[pctrans]

Anyone got the lube order? TM 9-2320-272-12?

 

[PowerstrokeNC]

Thanks everybody for the input...Ok, so as simple as drain existing fluid, add back in Dexron? No special procedure?

 

[PowerstrokeNC]

This just made me think of something else....what about the axles and Hi/Lo transfer case, do these have the right fluids or ....?

 

[BKubu]

I agree...Dexron. I had a truck at Allison for servicing once. They spotted 10W oil in the transmission and asked me if I wanted 10w back in or Dexron. I asked them what they recommended and they said Dexron. I was told that 10W and Dexron are basically the same, except Dexron has additives that help extend the life of the transmission. I don't care what comes out...Dexron always goes back in...at least with my HEMTTs and M939 series trucks. I suppose there COULD be another transmission in another application that requires something else.

 

[Ord22]

yes 73m819. you are right. we could get an abundance of the 10w than the dexron. it worked just as good. we seen the trucks with either 10w or dexron. i would go with dexron. make sure you change the filters. it gonna be a process to rid of all the 10w.

 

[BKubu]

yes 73m819. you are right. we could get an abundance of the 10w than the dexron. it worked just as good. we seen the trucks with either 10w or dexron. i would go with dexron. make sure you change the filters. it gonna be a process to rid of all the 10w.

Agreed. When I replaced the 10W with Dexron, I had to change the transmission fluid multiple times before all of the 10W was flushed from the system.

 

[PowerstrokeNC]

Valuable info, thanks everyone.

 

[GIJoeCzar]

Does anyone know how to do a transmission fluid exchange on the MT654CR transmissions in the M939 series trucks? Just dropping the pan gets so little and Allison replaces all of the fluid if they warranty a rebuilt transmission. Also, does anyone have a lead on a used, working, and cheap MT654CR transmission, preferably near Columbia, SC?

 

[spicergear]

For those of you that have chenged to Dexron, about how much fluid did you have to use to for the full flush in multiple times? I'm going to do this to my 932 and just want to make sure. Also, if anyone has the filter numbers handy, it would be appreciated.


Thanks!

 

[PowerstrokeNC]

For those of you that have chenged to Dexron, about how much fluid did you have to use to for the full flush in multiple times? I'm going to do this to my 932 and just want to make sure. Also, if anyone has the filter numbers handy, it would be appreciated.


Thanks!

I bought the Napa 5 gal's Dexron III (made by Valvoline) used approx 1 1/2 buckets, I was doing my Deuce at the same time so qty's are a little vague.

Attached doc on the filter numbers I have so far.

 

[PowerstrokeNC]

BTW on the doc the "2 1/2 ton" referred to in my doc is the A3

 

[Westex]

The latest and greatest for my 923 is TranSynd. It ain't cheap, though.

 

[quickfarms]

Yes transund is better than dextron for an over the road truck.

It has a increased service interval over dextron.

Our application is unusual due to the low miles driven per year.

Some over the road truck are driven more miles in a week than our trucks are driven in a year.

I run dextron in my truck