Best Trans Fluid

[Busnut83]

Which fluid for an allison 740 trans in a 83 mci-9 njt

[TomC]

You can use any Dextron rated auto fluid, as long as it says it is C4 rated for Allison transmissions.  I bought Pep Boys brand trans fluid.  If you want the best with the best possiblity of heat rejection and longest transmission life, use the Castrol Transynd synthetic transmission fluid.  It costs about $40.00 a gallon and you have to change the trans fluid twice to make sure you flush out the old fluid.  I might change here the next year.  Good Luck, TomC

[buswarrior]

Others with the first hand skinny should chime in...

Reports from those with temp instrumentation on their transmissions have reported a 10 degree Farenheit drop in operating temp by switching to synthetic.

Probably a good thing, since heat kills trannies.... expensive juice saves a more expensive rebuild?

happy coaching!
buswarrior

[NEO/Russ]

FYI - I have three five gallon pails of the Dextron Synthetic that I'd sell for less than the going rate, contact me off-line if interested.  russ barnes at mindspring dot com (compress the addy)

[Sean]

I can confirm the temperature drop with TranSynd.  We won't use anything else.

We have the 748HTB, which has an output retarder.  Boy can that puppy generate heat.  TranSynd was the best thing we ever did for it.

When PEDCO just finished inspecting my tranny, we had to refill with fresh fluid.  They offered me BetaLube ATF, a locally produced synthetic tranny fluid, for $28 per gallon.  We insisted on the genuine TranSynd product, and they had to send me over to Valley Power (the authorized Allison distributor) for ten gallons of it -- at $42 each.  Worth every penny, IMO.  This is my second complete change with TranSynd, though, so now I can go to the extended drain intervals, which should help offset the cost.  FWIW.

One downside:  we have some minor fluid seepage around the case.  The TranSynd made it worse, I think because it flows more freely through small orifices.  Not enough to want to pull the tranny and change gaskets -- even at $40 per gallon, I'd have to seep a ton of fluid before that would pay off.

-Sean
http://ourodyssey.blogspot.com

[Dave B]

An excellent seminar on Allison transmissions was presented at the last Bus'n USA rally in Oregon.  The presenter warned everyone about using the new Dextron VI in any 500, 600 or 700 series transmissions.  He said that GM has replaced Dextron III with Dextron IV effective January 1,2007.

He recommended TranSynd in all transmissions and noted the 10 degree drop in temp.  Other brands of synthetic were also suggested as long as they meet the TES-295 approval.  See http://www.allisontransmission.com/service/autoapp/172/viewpage.jsp?ThisPage=3

He said that it takes two drain & fills  before you can follow the extended change interval allowed by the synthetic.  You can reduce that to just one if the torque converter is also drained during the change to synthetic, but he said that you have to specifically ask the shop to do that.  Different transmissions have these drains in different locations.

[Dave B]

I forgot to add that they recommended a synthetic oil in the differential and manual transmissions also.  He has had good success with Chevron ESI synthetic oil.

[Sean]

...  Other brands of synthetic were also suggested as long as they meet the TES-295 approval.  See http://www.allisontransmission.com/service/autoapp/172/viewpage.jsp?ThisPage=3
...

Just FYI, all four of the other brands in that list are also actually Castrol TranSynd, re-branded through cooperative marketing agreements.  It all comes from the same plant.

Other PAO-based synthetic transmission fluids are probably just as good, but Allison won't certify them.  If your tranny is out of warranty, then going to an uncertified fluid and extending the drain intervals is probably not a big deal.  But what I have found is that authorized Allison dealers understand TranSynd, and behave accordingly if you tell them that's what's in it.  They treat everything else like conventional ATF.  FWIW.

-Sean
http://ourodyssey.blogspot.com

[belfert]

I have no reason not to believe Sean, but I also have no idea why ExxonMobil would sell Mobil 1 Delvac synthetic ATF if they don't even make it.  I have Transynd in my tranny in part because I couldn't find any of the other four TES-295 fluids for sale anywhere. 

I will say that the new tranny fluid has stopped my tranny from downshifting very hard into first when the tranny is cold.  The fluid was very bad in my tranny and new fluid, Transynd or not, may have helped this issue.

[Sean]

... I also have no idea why ExxonMobil would sell Mobil 1 Delvac synthetic ATF if they don't even make it.
...

The answer has to do with fleet lube contracts.  The four other players on the TES-295 list are all major fleet lube suppliers.  When their customers with Allisons started demanding Allison-approved synthetics, they had three choices:

1. Bite the bullet, and build their own test stand to Allison specifications (more on this in a moment), then pay Allison or a bonded third-party to witness the tests, so that they could have Allison approve a product from their in-house portfolio.  A multi-million dollar proposition, with a very, very long-term payback.

2. Go to Castrol, hat and billfold in hand, and make an agreement to buy and re-brand the one and only product that Allison had already tested and approved as meeting their TES-295 spec, so that they could then supply that re-branded product to their own fleet lube customers.

3. Risk losing lucrative fleet lube (and possibly fueling) contracts to other players, because some fleets insist on one-stop shopping.

To a player like ExxonMobil, #3 is just not an option.  So that left them with a cost-benefit analysis between #1 and #2.

The background (and angry debate) on this is old news, but for those unfamiliar with the story:  Allison and Castrol together built a multi-million-dollar test stand to Allison specifications, and Castrol did the tribology and lubrication/hydraulic engineering to formulate a PAO-based synthetic lubricant/hydraulic fluid that would meet Allison's criteria under controlled tests.  It was a major effort on the part of both companies.

What happened next is the ugly part.  There are many accusations and unsubstantiated rumors and we will likely never know the truth about what closed-door agreements Allison and Castrol had (that might be construed to be anti-competitive or monopolistic under certain interpretations of the law), but the fact that few dispute is that Allison destroyed the multi-million-dollar testing setup immediately after certifying the Castrol product and before anyone else could make a case that they should be given equal access to the identical laboratory conditions to have their own products certified.

Many angry recriminations followed, including lawsuits (AmsOil comes to mind) that were resolved ultimately in Allison's favor.  Allison avoided legal trouble by inviting anyone and everyone who wanted their product certified to build their own test setup (to Allison specifications) at their own cost.  Which was, effectively, a barrier to entry for many players.  I'm sure ExxonMobil or BP could easily afford to do it, but they have to balance that against the potential revenue stream of any product that resulted from it, and synthetic transmission fluid is an incredibly small fraction of their business.  (Besides which, the whole point of TES-295 fluid, for the customer, is to buy less of it, since it allows you to extend the drain intervals significantly.  No petroleum company really wants to be in the business of selling a product that doesn't need to be replaced as often.)

Allison, BTW, took something of a black eye over this whole fiasco, and eventually caved in to market pressure by approving two test labs in San Antonio, TX to test and certify products to the TES-295 standard.  My knowledge on this subject may be out of date, but, AFAIK, neither of those labs has built a test facility or certified any products.

I am open to being corrected about any of this, as the last time I delved into the subject in depth was when I made the decision for myself to switch to the synthetic fluid, which was some time ago.  It's possible that one of these four products is no longer re-branded TranSynd, and I just didn't get the memo.

-Sean
http://ourodyssey.blogspot.com

[buswarrior]

Thnaks for this Sean, quite interesting!

happy coaching!
buswarrior

[NewbeeMC9]

since we're on the subject,  I saw rotella 30 w on there, can you use motor oil in your alison auto.   i have the HT740.  I use the advance dexron since you can get it in the gallon jugs and i cant seem to get my modulator to stop leaking.

[justin25taylor]

since we're on the subject,  I saw rotella 30 w on there, can you use motor oil in your Allison auto.   i have the HT740.  I use the advance dexron since you can get it in the gallon jugs and i cant seem to get my modulator to stop leaking.

I have a very good friend/bus mechanic that swears it is fine to use HD 30w or Tractor hyd.oil like farm tractors use, Hy Tran etc. He has a model 10 Eagle with 900k on it and has always used it. He has never had a problem. I  am sure he has put it in many, many buses (with the customers OK)

Anyone else heard of this? Hytran is way cheaper than ATF.
Justin

[Sean]

... I saw rotella 30 w on there, can you use motor oil in your alison auto.   i have the HT740. ...

According to Allison publication 1390 ("Service Tip: Transmission Fluid Recommendations"), the following fluids are approved for use in 700 series transmissions:

TranSynd (and other synthetics tested to Allison TES-295)
Dexron-III
C-4 certified fluids.

There are some 30-weight motor oils that have been tested and meet the C-4 specification.  You can find the list on Allison's web site, here:
https://fdlrd.swri.org/Allison/ApprovedFluidsList.aspx?Id=1

If you select one of these oils, you should be fine.  Bear in mind, however, that to change from, say Dexron-III to C-4, you will need to purge the system of the Dexron-III.  I believe there is a procedure for this in one of the Allison publications.

Basically, you'll need to do two complete fluid and filter changes to ensure that all the Dexron is out and what you've got left is C-4.

All that being said, bear in mind there will be different operating limits with these different fluids.  TranSynd is good down to -22°F, Dexron-III is good down to -13°F, and SAE30 is only good down to 32°F.  So if you need to start your bus when it is below freezing, and you have SAE30 in the tranny, you will need to pre-heat the tranny fluid until it is at least above 32°F.  Allison says you can do that with a sump heater, or, if you don't have a sump heater, you can run the engine for 20 minutes with the transmission in Neutral before engaging any gear.

If I were you, I would stick with Dexron-III, if that's what's in there already.  I don't think you'll realize any savings switching to SAE30, and it's probably not worth the hassle.  FWIW.

-Sean
http://ourodyssey.blogspot.com

[Sean]

...  I use the advance dexron since you can get it in the gallon jugs and i cant seem to get my modulator to stop leaking. ...

Sorry for the double post, but I just re-read yours, and realized I left something out.

I hope, when you say "advance dexron" you are not talking about anything other than Dexron-III.  The newest stuff, Dexron-VI, and the older Dexron-IV are definitely NOT approved for use in the HT740.

In fact, if you've been using one of these, that might explain the leaking modulator (or might not -- I'm definitely not a tranny expert)..  If so, I would flush the tranny out and refill with Dexron-III.

HTH.

-Sean
http://ourodyssey.blogspot.com