New GM Dextron III-H for 2005

Butch 02 Sierra Denali · Dec 2, 2004

The bulletin from GM sent to dealers on Sept.3rd-'04 states this:
"GM has recently upgraded the Dexron-III ATF specification.
The upgraded specification is referred to as Dexron-III w/ "H-Revision". This upgrade will ensure that ATF's are commercially available to match the quality and durability of current factory-fill ATF. Fluids that meet the requirements of the H-revision are labeled as "Dexron-III,Approved for the H Specification"
Fluids labeled as Dexron-III "H' Specification can be used in any transmission application which specifies the use of Dexron II,IIE or III ATF's."

It does not say anything about it being synthetic or a synthetic blend, anyone know if it is, or why they changed the spec?

Butch 02 Sierra Denali

MolaKule · Dec 2, 2004

The newer transmissions are smaller, contain more components per volume, have higher power densities, and therefor run hotter.

Another concern was for the newer CSTC clutches -that they be free from shudder. So the newer fluid had to have a much improved Dynmaic Coefficient of Friction value.

GM wanted their new 5 and 6-speed "multi-gear" automatic transmissions to have a fluid with a longer life, greater oxidation resistance, more cleanliness, improved friction modification for new clutch materials, and greater overall stability.

The blender would not be able to use the older Group I paraffinic base oils with the new "H" spec.

The minimum base oil for the new spec has to be a Group II+ paraffinic. Many compounders, blenders, and formulators will be using a new additive package with the majority fluid coming from Group III paraffinincs, PAO (Group IV), and AN's and esters (Group V).

GM wants this fluid to be their lifetime fill for the 2004 and up automatic transmissions.

Ken2 · Dec 3, 2004

GM won't issue any more of the annual licenses for Dexron-III(G) next year...only -III(H). GM claims that (H) is good for 100,000 miles in normal service in a GM transmission. They've set a conservative limit of 50,000 miles for severe service, but the last I'd heard they were awaiting data to raise that to 100,000 miles, also.

I've read that Ford is toughening the Mercon® spec, also, but haven't seen any details.

I've got Schaeffer's #204SAT All-Trans ATF (Dexron-III(H) and other licenses) ready to put into my Volvo as soon as I finish the Auto-Rx cleaning.

Ken

Butch 02 Sierra Denali · Dec 4, 2004

Is the new spec oil considered synthetic or even semi-synthetic?
And does something like Mobil 1 ATF meet the spec?

Butch 02 Sierra Denali

1 FMF · Dec 5, 2004

quote:

Originally posted by MolaKule:
The blender would not be able to use the older Group I paraffinic base oils with the new "H" spec.
The minimum base oil for the new spec has to be a Group II+ paraffinic. Many compounders, blenders, and formulators will be using a new additive package with the majority fluid coming from Group III paraffinincs, PAO (Group IV), and AN's and esters (Group V).

from what I've read in the lube industry (about marketing) is anything with a group III, IV, V, or PAO can either be called semi-synthetic or full synthetic. There are no rules nor a solid definition for the use of the word synthetic.
We would be wise not to talk about this, next thing you know Dex-IIIH is relabeled as syn and the price is marked up.

quote:

the newer fluid had to have a much improved Dynamic Coefficient of Friction value

what does this mean in terms of shifting for a manual synchromesh transmission, as in the T-56 in F-bodies and Vettes which currently spec Dex-III? Can we expect to see better or worse shifting?

Ray H · Dec 6, 2004

quote:

Originally posted by 1 FMF:
what does this mean in terms of shifting for a manual synchromesh transmission, as in the T-56 in F-bodies and Vettes which currently spec Dex-III? Can we expect to see better or worse shifting?

I believe this "dynamic coefficient of friction" terminology is synonymous with "friction modification" - the chemistry that saturates the band and clutch facings in automatic transmissions to smooth shifts and elliminate torque converter lockup judder. Since the "H" spec is backward compatible with all previous DEXRON-III flavors, at worst you'll notice no difference in your manual transmissions' shifting ease. At best, you'll notice no more improvement than you'd have gotten with a flush and refill of the prior DEXRON-III.

MolaKule · Dec 6, 2004

Butch,

The new "H" fluid can be anything from semi-synthetic to full synthetic, depending on how the blenders approach the formulation.

quote:

I believe this "dynamic coefficient of friction" terminology is synonymous with "friction modification" - the chemistry that saturates the band and clutch facings in automatic transmissions to smooth shifts and elliminate torque converter lockup judder.

Right on Ray with a minor clairification.

It is not just the lockup shudder that concerned them. The new Continuous Slipping Torque Converter Clutch (CSTCC) shears the heck out of the fluid so the HTHS specs of the fluid had to be improved as well in order to prevent any stick-slip.

MaximaGuy · Dec 7, 2004

Yesterday, I stepped into a Kragen store and found Chevron DexronIII "H" spec fluid for $1.69. Not bad it is priced close to the G spec fluid....

Big Jim · Dec 7, 2004

quote:

Originally posted by Ray H:

quote:

Originally posted by 1 FMF:
what does this mean in terms of shifting for a manual synchromesh transmission, as in the T-56 in F-bodies and Vettes which currently spec Dex-III? Can we expect to see better or worse shifting?

Click to expand...

I believe this "dynamic coefficient of friction" terminology is synonymous with "friction modification" - the chemistry that saturates the band and clutch facings in automatic transmissions to smooth shifts and elliminate torque converter lockup judder. Since the "H" spec is backward compatible with all previous DEXRON-III flavors, at worst you'll notice no difference in your manual transmissions' shifting ease. At best, you'll notice no more improvement than you'd have gotten with a flush and refill of the prior DEXRON-III.

If indeed there is more friction modifier in the new fluid, you most likely will see an improvement in shift quality on manual transmission applications.

ATF+3 works much better in my Ford Contour MTX75 than the stock Mercon / Dexron III.

Butch 02 Sierra Denali · Dec 7, 2004

I wonder if the "H" spec can be used in pre 2005's or will it cause clutch or band slip?

confused · Dec 9, 2004

Is is possible to purchase the fluid that is used as factory fill in these GM transmissions?

T-Keith · Dec 9, 2004

quote:

Originally posted by Butch 02 Sierra Denali:
I wonder if the "H" spec can be used in pre 2005's or will it cause clutch or band slip?

I have it in three of my cars. 88, 97 and 98, and have had no problems yet.

MolaKule · Dec 9, 2004

The "H" spec is supposed to backward compatible to all previous Dexron fluids.

confused · Dec 10, 2004

Would anyone know if Citgo Transgard Dexron III / Mercon http://www.docs.citgo.com/msds_pi/355433.pdf meets the upcoming Dexron III-H requirements?

ChrisW · Dec 10, 2004

can the III-H be used in say a 94 Honda civic transmission that spec'd II-e? Or is it not backwards compatible in that particular way?

I have chevron dex III in there right now, and shifting is fine. Wondering if the III-H would improve shifts or whatnot.

Thanks in advance.

MolaKule · Dec 10, 2004

It doesn't appear to meet the Dexron III(H) specs.

It seems to be a general Dexron III(G)/Mercon type fluid.

New GM Dextron III-H for 2005

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