Just as the title says, I thought I'd post the info because it seems to be a common question. Just remember ALL Allisons are TES-295 compatable so if in doubt just use it, it's not much more money. It really IS a much better fluid.

Don't forget the Baltimore plant serial number break...

S/N 6310670488 and up for Indianapolis built transmissions, AND...
S/N 6320784373 and up for Baltimore built transmissions used in GM pickups.

Don't forget the Baltimore plant serial number break...

S/N 6310670488 and up for Indianapolis built transmissions, AND...
S/N 6320784373 and up for Baltimore built transmissions used in GM pickups.
How do you know if it is Baltimore VS. Indianapolis built? My tranny S/N is 6320722316. Cheers.

Look closely at the third digit in bold type.

Don't forget the Baltimore plant serial number break...

S/N 6310670488 and up for Indianapolis built transmissions, AND...
S/N 6320784373 and up for Baltimore built transmissions used in GM pickups.

Just making sure you were paying attention;) Honestly I didn't know about the Baltimore S/N cutoff being different.

Just making sure you were paying attention;) Honestly I didn't know about the Baltimore S/N cutoff being different.

The older version of the Allison document used to list them both, now has been revised to show only Indianapolis S/N. Since the sale of Allison by GM a year and a half ago, Allison has been removing information that pertains only to the GM pickups. 631... numbers are Indy, 632... numbers are Baltimore, 96... numbers are Reman.

They need to make the Serial# for Dex VI a BOLD lettered sticky with another Sticky right below it saying the 2500-3500 trucks have MANUAL t-case which use ATF. Just a thought

Looks like DexIII for me... Cheers.

Nichols - there is a sticky I wrote and had posted in the maintenance and fluids forum regarding the whole t-case/ATF issue.

Nichols - there is a sticky I wrote and had posted in the maintenance and fluids forum regarding the whole t-case/ATF issue.

I saw it but it seems like the t-case and tranny fluid question is asked weekly.:D

My serial # is 6320773474. So are you saying that I should not run Dex VI even though ALL of my manuals say otherwise?

im running dex 6, just had it swaped out at the dealer at 57,000kms this monday. Did internal and spin on also. I had also been running my predator on the 65hp tune for about 2 months, and the diesel mechanic said it looked as if it just rolled off the showroom floor. So thats re-assuring. He basically said right to my face, theirs no way youll blow this allison with an extra 40-85HP tune, hes been doing this for 35 years so i believe him!

My serial # is 6320773474. So are you saying that I should not run Dex VI even though ALL of my manuals say otherwise?

The OP is a bit misinformed, IMHO. I researched this til my head nearly exploded. The thread below has a TON of info with regard to this issue, happy reading.

http://www.dieselplace.com/forum/showthread.php?t=245178&page=3

631XXXXXXX numbers were built in Indianapolis now wholly Ally since the GM/Allison split. All Ally Service tips from 1099G and newer will not reference the 632....... serial numbers anymore. They have also blocked access to past ST 1099F that did list the two different cut off serial numbers.

632XXXXXXX numbers were built in Baltimore, now wholly GM since the GM/Allison split

As you will find out from reading thread linked above, it couldn't be anymore confusing if GM had absolutely tried to make it as confusing as possible.

Based on my research, you are still below the Baltimore plant cutoff number, but it is not an exact science and who really knows. I plan to replace my OEM fluid with Transynd TES-295 when that time comes, until then things are fine IMHO. This is an issue that will likely take a significant amount of time to manifest itself (viton seals hardening and cracking). Since it only applies to units with a standard 3yr/36k mile powertrain warranty, I have concluded that GM chose not to issue anything formally that acknowledged a potential problem, as it would likely not happen within the warranty period. Allison cannot legally post info on the units that they no longer own (63207....).

IS DEX VI gonna frag your tranny? NO. Will it potentially cause seal leakage over the long haul? Based on the only info available to us, it is possible. Your decision.

It seems that Castrol is no longer the vendor supplier for Allison. I needed a gal. and went to the local Allison rep and repair center to get it. Instead of Transynd I got Mobil Delvac TES295 Synthetic Transmission Fluid approved for all Allison transmissions. I asked about it and was told that is what they are getting now for the Allison HD transmissions.
What do ya think?
Max

It seems that Castrol is no longer the vendor supplier for Allison. I needed a gal. and went to the local Allison rep and repair center to get it. Instead of Transynd I got Mobil Delvac TES295 Synthetic Transmission Fluid approved for all Allison transmissions. I asked about it and was told that is what they are getting now for the Allison HD transmissions.
What do ya think?
Max

Both are Allison approved/certified TES-295 fluids, pick one. I would use either with the utmost confidence.

I wasn't worried about the fluid. Just wanted to get it out there that Mobil Delvac is now being used by Allison.
Thanks Jfarr.
Max:D

There are many trucks out there that are '06 model year, that have owner's manuals that state "DEXRON VI", and dipsticks that state "DEXRON VI", but are way before the cut off.

I'd steer clear of DEX VI if your truck is not after the cutoff for either series of tranny (Balt or Indy). DEX VI won't ruin the tranny, but it might cause leaks due to some incompatibility with the seal material used (in the pump body, IIRC - correct me if I'm wong).

Any TES-389 or TES-295 fluid will work just fine in all the pre-cutoff trannies.

In fact, the'll work fine AFTER the cutoff as well, but GM will might give you some grief, should you have a warranty issue. That is, if they are smart enough to even know the difference. Most (not all) service guys could not tell the difference, nor give a crap about it. When I bought some DEX VI at the dealership parts counter, they had no idea what it was; they even had to order it - it was not stocked! Go figure ...

I am against Dex 6 for the one reason that it is like a gel at -30. I will stick with Transynd in mine as I know I can rely on the fluid to flow at cold temperatures.

I suppose it is a guess to which fluid is actually in my 08' ally 632101.... I am close to changing the spin on filter for the first time and am down to flipping a coin, as to which fluid to purchase to top off after the spin on change. Compatability between fluids is the concern if I purchase the wrong one.

After further research it appears that the ally transmissions installed at the factory from January 1, 2007 through the 08's have Dexron VI from the factory. Starting with the 09's the ally's will have the new TES-295.

"Starting with the 09's the ally's will have the new TES-295." Where'd you get that info??? And what do you mean by "new" TES-295? I don't think this spec has seen any revisions at all since inception.

And, can you be more specific? The Baltimore plant is GM owned and run; they're likely to stick with DEX VI. The Indy plant is still true Allison, and they have always used TES-295 AFAIK.

Dish it up with links and references, if you have them, please.


Regarding the changeover dates, the main problems come from the fact that GM may have changed over to using DEX VI before the seals were updated for the chemical compatibility issue. This is why there might be DEX VI in the trannies, and "DEX VI" on the dipsticks and "DEX VI" in the manuals, even though the two plants were not yet installing the new seals. GM got the cart ahead of the horse, so to speak.

As far as I know GM has no plans to switch to a TES-295 fluid. DEX6 is GM's "common" ATF. They will maintain that it is fully backwards compatible in place of DEX3, though some have observed differences such as the Viton seal compatibility and cold temperature flow characteristics. The Viton seal compatibility of a DEXRON ATF fluid is shown by Allison TES-389 approval. DEX6 and even some DEX3(h) have been shown to cause hardening of certain types of Viton, with the most likely result being seal leakage.

The Baltimore transmission plant used a TES-389 rated DEX3 until the license expired at the end of 2006. This means that MOST 2006 and 2007 Classic trucks had a majority of DEX3, with DEX6 added at the truck plant to fill the coolers. If you have a new body style 2007 or later it will have DEX6 100%. The new DEX6 compatible seals were in by the start of 2007's. DEX3, DEX6, and TranSynd are okay to mix in any proportion.

TranSynd and Mobil Delvac ATF are both TES-295 approved and licensed by Allison Transmission, so their dealers can market either they choose.