Originally Posted by JHZR2
I thought that Zinc Esters (or is it only ZDDP?) were generally omitted from ATF because they turned red fluids brown?
Zinc compounds are still used in step-shift ATF DI packages as secondary anti-oxidants and metal deactivators, but in concentrations of < 5 ppm on the average.
Originally Posted by JHZR2
If that was the case, I'd think it means that the Zinc antiwear function can be accomplished by something else?
I had my colleague re-run another analysis (which I have been waiting for before responding further) and upon further inspection it appears the zinc component is a zinc dialkyldithiocarbamate which is a multi-functional additive that acts as an Antioxidant, Antiwear/Antiscuff, Corrosion Inhibitor, and Metal Deactivator, hence, a Multi-Functional chemistry.
Could an alternative set of chemistry be formulated to replace the Zinc DTC. Quite possibly, but what would it be?
Originally Posted by JHZR2
Even if not, if reduction of zinc in motor oils still yields an acceptable, if not a superior result, couldn't the same be achieved here?
Zinc reduction in motors oils, and specifically ZDDP compounds, are reduced to prevent metallic loading of catalytic converters, due to the possibility of metallic ash being carried into the exhaust stream and into the CAT. Transmission fluids of course never see combustion gases. I don't see a 1-1 comparison here.
Originally Posted by JHZR2
Is there something that the zinc we see there is doing, that absolutely nothing else can?
Quite possibly, but what would it be?
Originally Posted by JHZR2
I've not seen the actual standard written by Honda for DW-1. If it doesn't prescribe a specific zinc content, I don't think it is necessary to be there. Other performance attributes are the parameters of interest.
If zinc is not specified in the standard, then the presence or lack thereof of zinc seems to me to be an academic curiosity. And not the first time an oil supplier wouldn't comment on their additives...
As others have mentioned, if Honda has a standard, it has not been published and the original DW-1 is most likely a closely held internal formulation spec.
Reason for Analysis:
The analysis was conducted because of the many past discussions and questions here on BITOG surrounding comparisons of third party MV ATF's with respect to the Honda DW-1, Z-1, and the Idemitsu H.
In my Commentary and Opinion I stated this:
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Commentary and Opinion: The chemical signature for this ATF is essentially the same as Honda's Z-1 fluid and is indicative of fluids used in
Automated Manual transmissions. To the author's knowledge, no Step-Shift ATF chemical signature compares. Notable is the level of the Zinc compounds needed for the internals of Automated Manual transmissions.
Owners' of Step-Shift automatic transmissions should avoid using this product in any Step-Shift automatic transmission.
I continue to stand by that warning.
And here is the reason for the implied warning: In the beginning of Step-Shift AT fluid formulations ZDDP and other zinc compounds were used as the primary AW and AO agent. Later, it was found that metallic zinc,
at the concentration levels being used, was infiltrating the pores of the cellulose-based wet-clutch materials.
Wet clutch's of the cellulose-composite types need a certain amount of porosity in order to soak up (disengaged condition) and expel fluid (engaged condition) in order provide the necessary dynamic FM required during shift transitions, and to also provide
cooling of the clutch pack surfaces.
For a more thorough discussion of the "temperatures " encountered in AT operation, see:
https://www.bobistheoilguy.com/automatic-transmissions-study/
A Study of Internal Heat Generation and Its Effects on ATF
Zinc infiltration of the pores not only modified the fluid exchange process and modified the dynamic FM, but also accelerated glazing of the clutch pack surfaces.
Now, knowing the disparate ratios of zinc-to-phosphorus in DW-1 (or Z-1) to the signatures of currently marketed fluids for Step-Shift AT's, I think the warning still applies.
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Conclusion: While this article may not settle all debates, one should closely examine these analyses and educate themselves on the various offerings and claims in order to determine "suitability" for their vehicles' transmission.