Which is Closest to DexronIII/Mercon?

[tom slick]

Since DexronIII/Mercon is no longer a licensed spec. and was split into DexronVI and MerconV which of the two is closest to the DexronIII/Mercon spec.?

From what I have intrepreted around here it seems as though recommendations are made based on vehicle manufacturer but if the vehicle once spec'd a fluid (dexIII) that both new specs supersede wouldn't either be suitable replacement?

I understand recommendations based on manufacturers' TSBs for newer cars because the manufacturer has done testing but what about an older vehicle? It seems like an old TH350 automatic would run fine on MerconV but is usually recommended to stick with DexronVI because it is a GM spec. Conversely an older Mazda would get recommended the Ford Spec. MerconV but should run fine on DexronVI.

 

[HondaMan]

Tom,

If you are looking for a pure DEX III, look for Castrol Transynd. It is specified for Allison Transmissions but you will find it is a DEX III. Some argue it was the best DEX III on the market.
From what I understand, it is still out there in mass. Last I looked for it (within this year) I found a few Allison dealers with 'hundreds' of jugs.
It will be priced somewhat high.

 

[tom slick]

The question is just in general. The recommendations I see here seem to be more along the line of vehicle manufacturer rather then the actual property of the fluid.

 

[SecondMonkey]

I think the new Chevron MD3 fluid is a very close match to the old Chevron Dex III fluid. So far my '96 Jeep loves it, and it's always had a steady diet of Chevron Dex III in the past. Costco has it for about $26/case.

(it also says right on the bottle to use it where Dex III is specified)

 

[HondaMan]

Originally Posted By: tom slick
The question is just in general. The recommendations I see here seem to be more along the line of vehicle manufacturer rather then the actual property of the fluid.


Tom,

While yes the fluid I mentioned is for a specific product/company, there is no mistake, Transynd is a DEX III and as I mentioned while it is a dated product, some feel it was one of the best DEX III's available.

 

[PT1]

I just went with Mobil1 synthetic ATF in my last DEXIII application. I have 2 boat transmissions and an awd tcase that still take DEXIII both will get the M-1

 

[Whitewolf]

Originally Posted By: HondaMan
Originally Posted By: tom slick
The question is just in general. The recommendations I see here seem to be more along the line of vehicle manufacturer rather then the actual property of the fluid.


Tom,

While yes the fluid I mentioned is for a specific product/company, there is no mistake, Transynd is a DEX III and as I mentioned while it is a dated product, some feel it was one of the best DEX III's available.


Transynd was a DEXRON-III(G) approved fluid. However, it fell short of meeting DEXRON-III(H) requirements, so that just goes to show that synthetic is not the be all and end all!

 

[tom slick]

so which of the newest spec fluids is most similar to the old spec?

 

[Whitewolf]

Originally Posted By: tom slick
so which of the newest spec fluids is most similar to the old spec?


There are literally scores of specifications out there ... so I can't answer generally. If you can be more specific, I might be able to be of more help.

 

[tom slick]

Is DEXVI closer to DEXIII
or
Is MERCONV closer to DEXIII.

 

[Whitewolf]

Ok, my view. DEXRON-VI could be thought of as a DEXRON-III but with several times more durability. Again, in my view the MERCON fluid is somewhere in the middle.

 

[Ken2]

Dexron-III ATFs are made by just about every oil blender. They carry different names such as D-M or M/D or something similar. These would meet the Dexron-III licensing spec if that was still available.

Real, licensed, Dexron-III is made under a different name also, the Allison TES-389 spec.

So, you can get the real stuff.

MerconV is not that close to Dexron-III, but many of the universal fluids are OK for both applications if the label so states.

GM recommends Dexron-VI for all their Hydramatic transmissions that were previously spec'ed for Dexron-III. Transmissions from other makers that used Dexron-III are not included in this, including most GM Allison transmissions.

 

[tom slick]

Thanks guys.

If I am interpreting your answers correctly DEXVI, although different, is most similar to DEXIII.

what if you had a transmission spec mercon (not V), would DEXVI still be the recommendation since dexronIII and mercon were the same spec?

 

[Whitewolf]

Originally Posted By: Ken2
Dexron-III ATFs are made by just about every oil blender. They carry different names such as D-M or M/D or something similar. These would meet the Dexron-III licensing spec if that was still available.

So, you can get the real stuff.


Actually NO. Once GM removed their license control from 'DEXRON-III' products many companies reverted to the earlier DEXRON-III (G) type formulations because they are more profitable even though the performance is lower. That is not to say that there are not some honest people out there, it's just a question of finding them. If you can identify one!

 

[benjamming]

Whitewolf,

You snipped out of your above quote:

"Real, licensed, Dexron-III is made under a different name also, the Allison TES-389 spec."

Any comment on this?

 

[Whitewolf]

I wasn't avoiding that piece of the question. I was simply answering one piece of the question. If you want to address the 389 'spec' then as far as I'm aware all that it requires is a reassurance from the company requesting approval that the formulation for which they are requesting the approval ever had a DEXRON-III(H) approval. Does Allison police this? I don't know. Do they have the ability to do so? I don't know. The simple answer is that, again, anybody can claim anything, but without a policing organization in place, it's meaningless.