What is better (oil or trans fluid)

[Ferroequinologist]

I changed over to ATF in the M915 I got. And wow, what a difference! smooth shifts and runs cooler (now, was running hotter for some reason but it has calmed down)

I also was like why change it if it had been working? but AMGeneral swore to do it, and I trust him, and I have to say, I'm very glad I did.

BTW I put 2500-10k miles a month on it.

 

[Danl]

Danl M915A1

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.

My truck has atf in it and it is clearly marked at the dip stick, my 915 was over hauled in 06 and may of been put on ATF at that time, If you want to use Atf instead of oil, in cold climent Like Here in Maine atf runns well cold 15 40 is sluges untill the oil warms up, sometimes the tranny will not shift gears untill the oil is hot. To get that ****ty oil out of the converter, You have to use a good tranny shop with a good Power flush unit cost maybe 200 Bucks on the high side, but have them fill it with Mopar ATF dodge Tranny oil is Allison Speck

 

[trukhead]

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

Thanks!

Yes, the tranny needs to come out and get dismantled completely as far as I know.

I changed over to ATF in the M915 I got. And wow, what a difference! smooth shifts and runs cooler (now, was running hotter for some reason but it has calmed down)

I also was like why change it if it had been working? but AMGeneral swore to do it, and I trust him, and I have to say, I'm very glad I did.

BTW I put 2500-10k miles a month on it.

Aircraft mechanic trained higher up in a national transportation fleet who now owns a newly purchased 4,000ish miles M35A3 who I sold 2 new tires to told me that oil is slipperier than atf ( some atf is designed with a higher friction coefficient).
So aft holds the clutches with less slippage-hence less wear and less heat generation and build up than straight engine oil in the transmission.
Most all oil and atf came from the same dead dinasours and prehsitoric plants but it is the additives that the engineers spec into the oil and aft that allow the rodeo of motion, friction and heat to occur in a reliable fashion in that wondrous gadget called a tranny. I wonder if high mileage trannys have too much out of spec wear that occurred between the surfaces that the aft swap flush will cause problems?!..
The question is how many miles does a tranny go before it has reached the point of no return...............