what oil should i use for the allison 5 spd automatic in my 1984 m925

[cjmorty]

I have 2 M925 cargo trucks withe the allison 5 spd A/T, can anyone please tell me, what type of fluid I should use for topping off what was there when they came out of the service, and what type of fluid for a complete change if different. Thanx...cjmorty

 

[FullSpecial]

DextronIII. There is like three or four different things you can use. Swear mine had hydraulic fluid in it. Shifts a lot better after a service.

 

[Coffey1]

The Tm's call for 10w oil
Allison says rotella t6 ( off road )
Dex ( Highway )

I would recommend taking to someone to change so they can get all oil or dex out of converter and oil cooler.

Dex has a lower boiling point so would not be good for heavy off road use.

 

[porkysplace]

I have 2 M925 cargo trucks withe the allison 5 spd A/T, can anyone please tell me, what type of fluid I should use for topping off what was there when they came out of the service, and what type of fluid for a complete change if different. Thanx...cjmorty

You should start wiyh downloading these ;
[h=3]TM's for the 939 series trucks[/h]
This will answer your fluid question on what the military uses : LO9-2320-272-12.pdf

 

[two.fiveM35]

Go a search on this topic, there has been lots of discussion on this topic. TM'S calls for 15/40w motor oil I believe

 

[cjmorty]

Thank you for the help, mine have a clear fluid currently. Do you know if it is okay to mix fluids ?

 

[porkysplace]

Thank you for the help, mine have a clear fluid currently. Do you know if it is okay to mix fluids ?

The fluids won't mix that's why a full flush is required to change to a different grade of oil. Have you downloaded and read the -10 TM ? Reading this will save you big money from repairs caused by improper shutdown and not using reverse in low range.

 

[Tow4]

I used this.

 

[Artisan]

Motor Oil is what it came with.

Get the TM's and the LO HERE

The hard downshifting is (if it bothers you), IMO, a really new tranny!

I towed 7 like trucks and it took that edge off my tranny.
I HATED my tranny before I towed those trucks, NOW I LOVE IT!

It needs to be USED a bit! There tactical vehicles! Not KW roadgirls !

The engine, tranny and power steering all take the same oil.
If you change it you now need to carry another oil...and your
changing the OEM specs.

It is REALLY HARD to do better than original engineering specifications.
Those TM's are your friend, they are a PITA but worth the time.

Caveat Emptor

 

[Rifleman]

I own a M925 too, so far i have only run what's listed in the TM's. The TM's list 10 weight motor oil for the trans and i have to say when i first got my truck (only 6 hours on hobbs and 38 miles on speed o) the transmission shifted hard from 2ND to 1ST,so i was thinking about changing to Dexron111, but after putting a few hundred miles on my truck the transmission shifts real smooth now without changing the oil.

The reason why i am going to stay with the 10 weight motor oil is my truck uses the same oil in the power steering pump along with the HYD tank for my winch and the transmission. By staying with the 10 weight oil i now only have to carry two types of oil for my truck, Rotella 15W40 for the engine and 10 weight for everything else.

One more point that Another S.S.member pointed out to me, the United States Military has used these trucks all over the world, under all kinds of sever conditions, from the arctic cold to desert heat and the 10 weight oil has worked well for them, so if it's good enough for our military, it's good enough for me. YMMV

 

[wreckerman893]

The fluids won't mix that's why a full flush is required to change to a different grade of oil. Have you downloaded and read the -10 TM ? Reading this will save you big money from repairs caused by improper shutdown and not using reverse in low range.

I had transmission fluid puking out of the fill hole on the M927 with the 250 Cummins in it after driving it in the snow the other day. I went to the Allison transmission shop and had a long talk with their senior tech. I told him the problem and he said the breather cap was plugged. Problem solved there. I also told him I had changed the fluid in my new M923A2 but was concerned that there was still oil in the torque converter.

He said that there was no problem with having 10 weight being mixed with the Dextron. This is from the horse's mouth boys and I'm going to run it and see what happens