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Topic: Use of SAE 15W40 motor oil in Allison HT746 (Read 3244 times) previous topic - next topic

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #25 –
Peter,
This is the exact procedure I have heard proposed many times by Allison engineers at FMCA transmission sessions.
Paul
Paul
36' 2000 U320
2014 Jeep Grand Cherokee Summit

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #26 –
Am I mistaken when I do the math here? If you change to TranSynd now, you are going to have to make one more change in the life of your motorhome regardless if you do a second change 30 minutes later as Tom suggested or wait until the normal Dexron change mileage and then do it. It still adds up to purchasing a TranSynd fill twice (unless you get a bad oil analysis back) in your motorhome's life. 

Following Tom's suggestion would have the advantage of full TES-295 compliance from the change over immediately. I have been accused of being cheap but is waiting not false economy? As he suggested, doing oil analysis on the fluid condition rather than the mileage may be the way to go to get the best use/cost out of the TES-295 spec fluid.

Tom's quote:

"Here's what I mean by a double drain and refill.  Drain the old fluid, refill with TranSynd, drive around for 1/2 hour (approx.) just until the fluid is warmed up and circulated through the torque converter and cooling system.    Then, drain again, change the filters and refill with TranSynd.  At this point you're good to go for the maximum recommended drain intervals.    If you really want to maximize the utility you get from TranSynd (miles/dollar), start doing oil analysis and change based on fluid condition instead of the recommended change intervals.  Allison publishes this but it's in the small print.  I know because I wrote the small print."

End quote.

Disclaimer: Allison trans with retarder may differ in the change schedule.

I have the skin of a crocodile so don't be afraid to take issue with my post. (may snap like one too)
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #27 –
Isn't it possible to do a flush by draining, refilling, disonnecting cooler return line, starting engine, stopping when clean fluid is returned?  Don't know if that flushes the torque converter or just the cooler, anyone?

Chuck
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #28 –
Quote from: Chuck Pearson –
Isn't it possible to do a flush by draining, refilling, disconnecting cooler return line, starting engine, stopping when clean fluid is returned?  Don't know if that flushes the torque converter or just the cooler, anyone?

Chuck

You might be able to do this, but it is not what Allison recommends.  No problem with a warranty though as there isn't one.  How would you be able to tell the difference between old fluid and new fluid unless it has a different color?  Mobil Delvac synthetic meeting Allison TES 295 specs is the same red color as Dexron.  Are you sure the old stuff would come out first?  Are you sure that draining out that much fluid with the engine running would not damage the transmission? 

I tried to remove a cooler line to drain as much of the old fluid as possible.  I had a huge adjustable wrench  and could not loosen the nuts.  One would run the risk of getting dirt in the line.  I did get out an extra quart or two by draining the transmission and filters, closing it back up, let it sit overnight and draining it again.  I thought that maybe the fluid in the converter might slowly drain into the sump, but it didn't.  The extra quart probably drained off the gears. 
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #29 –
FWIW, here is a link for a listing of Allison TES 295 approved transmission fluids.

Allison Transmission

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #30 –
The procedure used by Reliable Transmission , a Allison service center in ATL is :
Drain tranny, remove filters, Remove main fluid line to retarder and direct into bucket, START from rear and when tech hollers shut down.  This pumps a great deal of fluid from tranny and does no damage.
They have been the only ones to service mine and only problem I have had over the years is  a tech's failure to properly torque filter covers resulting in a minor leak that they fixed without charge and with an apology.

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #31 –
Gary, am I reading this right, the drain procedure at retarder happens before the transmission is refilled with new fluid? 

As far as telling when new fluid is flowing through using the disconnected return line for cooler,  no problem.  The fluid in my trans is golden yellow in appearance, I am told it may be Transynd as it tends to lose its red color.  It looks suspiciously like motor oil which I hope it's not....  Will collect a sample and send to Blackstone during the drain though identifying fluid is not a given through anaysis.  There

I am in a fever to get the old stuff out and as much new Transynd in as possible. 

Chuck
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #32 –
That's right Chuck, what you are doing is pumping all the old fluid out of the tranny that you can.
Gary B

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #33 –
Gary,

I am surprised the engine is started BEFORE the new fluid is put in.  Where is the pump getting the fluid to pump through the converter and retarder?

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #34 –
Brett, I am assuming that pump is simply pushing remaining fluid out.  This shop is famous for maintaining city garbage truck trannys and several MH owners in the area use and swear by them so I have to ASSUME that they know what they are doing.  When tech has me start up its only a few seconds til he yells to shut it off so it does not take long.  It is a two person job I could not do it by myself.
Gary B

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #35 –
Tom,

What interval do you suggest for oil sampling while using Transynd?
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #37 –
I wonder why the 4000 series isn't listed.  Has anyone installed the recommended tap.  In fact, has anyone been regularly doing analysis on their trans fluid?  What results have you found?  I guess I'll start 25,000 mile sampling through the dipstick and see what I find.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #38 –
Quote from: Pierce & Gaylie Stewart –
Tom,

On another transmission question. Is it possible for a Allison HT746 not to go into lockup? If it did not, would this result in elevated transmission temperatures? Would an owner be able to see this by reading the code by pressing the transmission switch under the flip up dash and reading the flashes from the bulb or would a specialized reader be required to retrieve stored codes? Most likely culprit?

Thanks in advance.

If the transmission does not go into lockup, it could cause higher temperature because you could have some frictional heat built up in the fluid.  Lockup mechanically ties the torque converter pump and turbine together so they become coupled and rotate at the exact same speed.  Otherwise, if not locked up, you could get some internally shearing in the fluid.  And, of course, if the lockup clutch is trying to apply but will not lockup due to a worn clutch, then friction would build up there too.  You should be able to feel that though.  It would act like a slipping clutch and you'd here it in the engine.  I'm not sure about reading the code, that's out of my area of expertise.  You'd need to call an authorized Allison dealer for that or call the technical help line listed on Allison's website.
Thomas L. (Tom) Johnson
Allison Transmission Fluids Engineer (Retired)
President, JG Lubricant Services

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #39 –
Tom,
I am one who appreciates your expertise,
Thank you.
 

Re: Use of SAE 15W40 motor oil in Allison HT746

Reply #40 –
Me, too.

I called Tom's company today (weekend) and expected to reach a recording.  Got Tom instead.  A real gentleman and a heck of a good customer service man.  He deserves our business support. 
George Stoltz.  Retired from full-time living in a great Foretravel and now are back to living in a traditional sticks and bricks in Florida.