What is better (oil or trans fluid)

[diverman555]

What do you guys think is better, the TM show that the military uses oil in the allison trans but Allison says you can use regular trans fluid. What do you think is better. My new truck came with the trans full of new oil and I was thinking about changing it to Trans fluid but then you have the converter to try to drain.

 

[gimpyrobb]

I have heard that you should put ATF in them. I have also heard that you can never get all the oil out so, 6 of one- half dozen another. I say run it if its working, why make extra work for yourself.

 

[Navo]

I have heard that you should put ATF in them. I have also heard that you can never get all the oil out so, 6 of one- half dozen another. I say run it if its working, why make extra work for yourself.

I agree. I dont think the 15-40 oil and ATF or Dexros III fluid are compatible. And like stated above you will never get it all out. So then you will be mixing the fluids and that may cause excessive wear and damage.

Of course I'm a noob here, so I could be completely wrong....

 

[gungearz]

ATF all the way...

 

[Navo]

ATF all the way...

SEE! I learned something new! Apparently it doesn't matter if you cant get it all out.

 

[trukhead]

SEE! I learned something new! Apparently it doesn't matter if you cant get it all out.

Whoaa little dooggie, Hold on there!

what truck are you referring to? also remember it isn't just a single drain and fill and yer golden. It took 3 drain and fills then a drain and pan drop and filters for my m35A3 and the transmission shifts as smooth as kitten wiskers. It was stated here on SS that a member called Allison and an engineer there very familiar with the 1545 said it was designed for Dexron III. THat being said.

What transmission do you have, how severe are you running. Allison make very specific reconendations for their trannies. Allison recomends oil in their big trannies in severe usage conditions.

opcorn:

 

[Navo]

Whoaa little dooggie, Hold on there!

what truck are you referring to? also remember it isn't just a single drain and fill and yer golden. It took 3 drain and fills then a drain and pan drop and filters for my m35A3 and the transmission shifts as smooth as kitten wiskers. It was stated here on SS that a member called Allison and an engineer there very familiar with the 1545 said it was designed for Dexron III. THat being said.

What transmission do you have, how severe are you running. Allison make very specific reconendations for their trannies. Allison recomends oil in their big trannies in severe usage conditions.

opcorn:

Im not sure of the original posters intent with the truck. I'm still in informational gathering stage at the moment. I hope to get an A3.

Thats what I was thinking, multiple fluid flushes etc. For my application it wont be doing any heavy work. Maybe just a load of rock or mulch now and then...everything else will be joy riding

 

[trukhead]

Im not sure of the original posters intent with the truck. I'm still in informational gathering stage at the moment. I hope to get an A3.

Thats what I was thinking, multiple fluid flushes etc. For my application it wont be doing any heavy work. Maybe just a load of rock or mulch now and then...everything else will be joy riding

Your intended uses match my uses and no heavy work. The transmission shifts great. I hope a yearly drain and refill will keep the tranny fresh and operational for the life of the truck.

by the way some have had the problem of after the flush 4rth gear and reverse go out due to an o ring going bad and that clutch slipping. I took a chance because my tranny was low mileage. Do a search.

 

[Navo]

Your intended uses match my uses and no heavy work. The transmission shifts great. I hope a yearly drain and refill will keep the tranny fresh and operational for the life of the truck.

by the way some have had the problem of after the flush 4rth gear and reverse go out due to an o ring going bad and that clutch slipping. I took a chance because my tranny was low mileage. Do a search.

is that o-ring something that you have to drop the tranny for? I will try and do a search on that later.

Thanks!

 

[diverman555]

It is a M923 5 ton and a Allison MT654CR trans.

 

[bearboley]

I would use what's in it and working. Why re invent the wheel. If there was a chance that after I changed oil a o ring in a clutch pack would go bad I would not do it,the service bill would be more than the truck cost.

 

[tie6044]

It would be nice if there was a way to flush the tranny. When I change the fluid on my civy trucks I take them to a local 4x4 shop and they hook it up to a machine that circulates the old fluid out, then runs a cleaner through, then the new tranny fluid. I would have to imagine that that process get all the old fluid out. They have a box full of adapters for each type of vehicle, my guess is they don't have one for trucks that start with "M".

 

[kennys@wi.rr.com]

Having done the flush and fill method and being in the middle of another one now I have to say it's the best way. I did trukhead's. I actually did it 5 or 6 times, I honestly forget. We bought 15 gallons in three pails from Napa. Used almost every last drop of it too. I hope to be the proud owner of an M939 series here in short order and that is one of the first things I am doing to the truck. Yes it cost a bit to do it. but the way I look at it is ATF is one of the best injector cleaners around and I will have an aweful lot of injector cleaner.

Please note it is not simply drain the pan and refill then you are good to go. Nor is it drain the pan, fill the pan then drain the pan again and you are good to go. You have to take the truck out for a series of short drives. 5 to 10 the first drain, 10 to 20 the second, working your way up to about a 30 to 40 mile drive. And do not forget reverse. I do at least a half mile in reverse on each drain. You will read threads where guys have blown their trannies after they changed fluids. that is becasue they either didn't flush and fill numerous times or they forgot the truck needs to be running and warm before they check the fluid level. I have no idea of who would ever do such a thing like forgetting when to check a level and then panic when the truck won't shift.

 

[kennys@wi.rr.com]

It would be nice if there was a way to flush the tranny. When I change the fluid on my civy trucks I take them to a local 4x4 shop and they hook it up to a machine that circulates the old fluid out, then runs a cleaner through, then the new tranny fluid. I would have to imagine that that process get all the old fluid out. They have a box full of adapters for each type of vehicle, my guess is they don't have one for trucks that start with "M".

This is actually a great idea. With the A3, can't say for certain on the M939 yet, you could remove the lines at the external filter and set up a pump system here. There is nothing different about the connections in that filter than any other trans line out there, with the exception that these are larger. That can be solved with a quick trip to the local hardware or Eaton store. If I was doing these on a regular basis I would have myself set up for it.

 

[nf6x]

With the A3, can't say for certain on the M939 yet, you could remove the lines at the external filter and set up a pump system here. There is nothing different about the connections in that filter than any other trans line out there, with the exception that these are larger. That can be solved with a quick trip to the local hardware or Eaton store.

If I'm not mistaken, the M939 series has a spin-on transmission fluid filter and heat exchanger in the engine compartment. That makes me wonder whether there may be a good way to flush out more of the old oil in each pass compared to the drain/fill/drive/repeat method, and possibly even reduce the amount of waste fluid left over at the end. If my M923 had a multifuel engine then that waste fluid might end up in the fuel tank, but I don't know if that's a good idea on the NHC250.

 

[kennys@wi.rr.com]

When I was an owner operator I used to dump all my drain oil in after an oil change and at every fill up I added ATF as an injector cleaner. I wouldn't use a full tank of the stuff, but when mixed in with what's already there you should be fine. But like I said I don't think I would do a full tank of the stuff.

 

[jwaller]

swap it and put ATF in it. then take the oil and burn it as fuel. all the issues I've had with the allison have been fixed by swapping to atf.

 

[renovate7]

There's a lot of good info and discussion on this in the Deuce forum. All the M35A3's came with motor oil in them. I changed the fluid 3 times in my A3.
The 5 tons have a different Allison tranny, not sure if that will make a difference. When all else fails call Allison.

 

[markmontana]

It is a M923 5 ton and a Allison MT654CR trans.

Diverman- here is the operators manual for the MT654CR:
http://www.allisontransmission.com/servlet/DownloadFile?Dir=publications/pubs&FileToGet=OM1334EN.pdf

And if you like that- here are all the pubs related to the MT654CR:
MT 654CR: MT 600 Series: Browse By Transmission Series: Publications: Allison Transmission South America

And when I get time, I am going to FLUSH the oil out and replace ATF in my 939 series trucks.

Enjoy!

 

[flibob]

Not to burst anyone's bubble but I'm going to dance with one what brought me. ie The military has run these things or not run in some of the worst conditions imaginable with military fluids for over 30 years. If you are buying a brand new tranny by all means do what the manufacturer recommends. As has been stated when you change horses in the middle of the stream you may bring on some unanticipated problems. Different people have different preferences. Both sides have their good points. Read then decide.