LMTV M1078 Transmission Fluid Change To ATF Write Up

Levelox said:

...t has anyone ever heard of being able to change Allison shift points electronically with a programmer? I was hoping to get smoother shifting from it...

During Hurricane Harvey me and 3 other guys with big trucks rescued 156 patients from an old folks home that were wheel chair bound or otherwise compromised. They swat team drowned out their high water vehicles and they were happy we showed up on the scene. Another reason I changed ALL fluid was because we were in 5' plus water for 8 hours that day.

Click to expand...

pretty sure that there is a programming difference between A0 and A1 so helps to know what you have.. .
There is some threads in here on this topic though. Maybe search for variations of the combination: "shift points", Program

Glad to hear you steeped up to help out

so after reading all these post still lost on which atf to use in my lmtv

...delete

Sprirax developed by Shell and Allison. Don’t out motor oil back in it like some people will tell you.

I'm one of the guys who would tell you to put motor oil back in it, the one you aren't supposed to listen to.

OK good for you. You’re entitled to be wrong if you want to be.

Use spirax Developed by shell and Allison

I don't think the personal attack is really warranted, is it? The engine oil is fine. It's been fine in my truck and it's fine in the military trucks or they wouldn't be doing it - or having been doing it - as long as they have.

Plus there are real advantages like it's cheap and you only have to carry one set of spare fluids on a long trip, which I actually do, so actually appreciate.

aleigh said:

I'm one of the guys who would tell you to put motor oil back in it, the one you aren't supposed to listen to.

Click to expand...

Levelox said:

OK good for you. You’re entitled to be wrong if you want to be.

Click to expand...

Yeh aleigh don't you know the military is wrong to want to stick to one type of lubricant? Just because they run fine over thousands of miles using said lubricant doesn't mean it works.

I wasn’t personally attacking you. You kind of did that to start. Let’s just agree To disagree and you can put Motor oil in whatever you’d like to. Allison worked alongside shell and develop a transmission fluid specifically for the Allison transmission. The military used oil not because it worked well but so they wouldn’t cross contaminate. You sure wouldn’t want to put transmission fluid in the crank case. Instead of arguing back-and-forth maybe we should just give the guy advice and let him decide. Seems every time I post anything I get something from somebody like you sniping back. It’s really not worth it. No need to respond. Have a nice day.

So for the person who was asking, Allison is going to tell you to use a C4 fluid if you call them (this is what they told me), for off-highway or severe-duty use, or, Transynd. Dexron 3 is an Allison C4 fluid but so are various heavy duty engine oils including Mobil. Also if you call an Allison shop that works on equipment (vs. over the road trucks) regularly they will tell you they put engine oil in them all the time. So it's fine. Really. And you can carry one fluid so when you leak engine oil (happened to me) or crack your transmission cooler and lose transmission fluid (happened to me) you are good to go.

I got nothing against ATF for the record. I hear it produces nicer shifting for some. Mine shifts OK already. I just have a problem with the notion there is a problem with engine oil in this particular application.

I had my truck at an Allison authorized repair center doing some troubleshooting on another issue and I asked that they flush and swap fluids if they thought it would be beneficial for longevity, they took an oil sample and told me it would be a waste of money. They recommended I leave the Military oil in it. I've only put about 2500 miles on the truck so far but I haven't had one issue I could relate to the transmission running oil.

I didn't see levelox's reply as an insult. It's your right to use whatever you want in your trucks transmission. As it was said before , The Army just uses oil as it is simpler and it is one of the fluids specified by Allison to work in the FMYV transmission. I won't last as long though. which is not an issue for the Army, because a) they have near unlimited resources. b) the trucks don't drive much in general.
BTW did you guys know that 'transmission fluid' is really an oil. But they are worried people will pour Engine oil in the transmission if it was called Transmission OIL.

Me for my part will use Allison synthetic Transmission Oil.

branr1 said:

I had my truck at an Allison authorized repair center doing some troubleshooting on another issue and I asked that they flush and swap fluids if they thought it would be beneficial for longevity, they took an oil sample and told me it would be a waste of money. They recommended I leave the Military oil in it. I've only put about 2500 miles on the truck so far but I haven't had one issue I could relate to the transmission running oil.

Click to expand...

Harsh shifts is one of the results. I know it because I did the change before and the shifts are much better, especially when cold. PS. Does that Allison repair guy buy you a new transmission, in case his opinion was wrong and changing the fluid wasn't a waste of money after all? I would have asked him that!

319cssb said:

Harsh shifts is one of the results. I know it because I did the change before and the shifts are much better, especially when cold. PS. Does that Allison repair guy buy you a new transmission, in case his opinion was wrong and changing the fluid wasn't a waste of money after all? I would have asked him that!

Click to expand...

Why so rough on the Allison tech? The military has 100,000 of these trucks with oil in the transmission, for some VERY intentional reason that nobody still seems to know - best I've heard so far is that oil has a higher boiling point than ATF. I've driven LMTVs with oil in the transmission that shifted really hard, or barely noticeable at all. The change to ATF on mine yielded no benefit that I can discern, so next time I drain it for some reason I may go back. I'm really interested to find out some concrete reasoning behind the oil in there, and it seems like many of the opinions to change it to ATF aren't really based in fact/science/evidence/engineering/etc.

Here is another negative for leaving the motor oil. In cold environments it can be quite viscous, and a mechanic I know said on about 40-50 FMTV/LMTV’s he has serviced, he found the trans filters crushed. He believes it’s from the vacuum created at the filter when the oil can not freely pass through from being viscous.

Warm environments shouldnt be an issue.

DiverDarrell said:

Here is another negative for leaving the motor oil. In cold environments it can be quite viscous, and a mechanic I know said on about 40-50 FMTV/LMTV’s he has serviced, he found the trans filters crushed. He believes it’s from the vacuum created at the filter when the oil can not freely pass through from being viscous.

Warm environments shouldnt be an issue.

Click to expand...

That information is actually called out in the Allison operator's manual. It states pre-heating is required:

SAE 0W-20: -22 oF
Dexron III: -17
SAE 10W: -4
SAE 15W-40: 5
SAE 30: 32
SAE 40: 50

DiverDarrell said:

Here is another negative for leaving the motor oil. In cold environments it can be quite viscous, and a mechanic I know said on about 40-50 FMTV/LMTV’s he has serviced, he found the trans filters crushed. He believes it’s from the vacuum created at the filter when the oil can not freely pass through from being viscous.
Warm environments shouldnt be an issue.

Click to expand...

You have the logic backwards. That's a reason to use oil, and NOT use ATF. The Army could have easily chosen to leave the ATF that the transmission typically uses in commercial applications alone, and use it in a wide range of temperatures, but instead they chose to switch to oil that they have to change to a different viscosity at a couple different temperature ranges? It sure seems like they had a really important reason to not use ATF, and to use oil instead. These decisions are not accidents or blunders.

The -20 manual says to use 15W40 above 40°F, straight 10 in -15 to 40°F, and special "arctic" oil -15 to -50°F (without specifying the properties of the special arctic oil).

That choice of oil is probably why they chose to alter the normal Cat bypass coolant flow and route it down to the transmission oil cooler. Normally the warm coolant coming off the head would flow back to the plugged port on the top of the water pump to recirculate in and warm the engine faster.

As plummed in the LMTV, most all the engine heat goes to the oil cooler, untill the thermostat opens, to warm the transmission oil at the expense of engine warmup...

Awesomeness said:

and special "arctic" oil -15 to -50°F (without specifying the properties of the special arctic oil).

Click to expand...

Funny enough the Allison op manual does define it, MIL-L-46167B.