Best trans fluid?

[KnightOwl]

Havent bought ATF in awhile except Mercon LV for the Ford. It looks like Dexron is kinda hard to find on the shelf. Dex/Merc. Transmax. and several others. Whats the popular choice these days for the 4T65e?

[KnightOwl]

Some other sites seem to highly recommend Valvoline Maxlife?

[digitaloutsider]

Just use Dex VI. How are you having trouble finding it? It's literally on every parts store shelf, even Walmart.

[Imp558]

Wasn't there something about Dex III and Dex VI shifting differently?

[FordMan77]

Yea, that has been debated.  When I did my trans replacement on my 00 GT I filled it up with Dex VI.  It's still living after 150K miles.  Didn't notice any weird junk in the pan when I installed my trans-go kit and did a pan drop/filter change over the winter.  No shifting issues either.  It either shifts fine or if it's slipping then it's already on the way out.

 

Run the Dex VI and call it a day.  Just don't flush the trans. or you will likely be replacing it shortly.  And FYI, the last time I used Valvoline trans fluid it came out already smelling burnt, lol...  Not sure if they have changed it since then.

[Schurkey]

Best trans fluid?  One-word answer = CLEAN.

 

The only "Dexron" fluid that currently exists is Dexron VI.  Good ol' Dexron III is no longer licensed by GM, therefore anyone still making it cannot use the "Dexron" trade-name.  Therefore, that's the Dex-Merc you see on the shelves.

 

In a transmission made before GM switched to Dex VI, I feel just fine using Dex-Merc in it.  If it was originally spec'ed with VI, use VI.

 

 

 

 

Any transmission that fails after a properly-done fluid flush would have failed anyway.  A fluid flush does nothing evil to a transmission.

[KnightOwl]

I just did a pan drop-n-drain along with filter swap. Most of the fluid on the shelf in the local parts stores are either the Dex/Merc universal type or the Mercon LV or Type F (this would be AutoZone, Advance, and O'Reillys) I wound up going with one of the Dex/Merc types since it is supposed to replace Dexron up to VI (2005-up)

 

I was happy to see the fluid that came out was still red and not burnt smelling at all...very little residue in the pan. Now that I have the ZZP pan with drain plug I can drain-n-fill.

 

Thanks guys!

[digitaloutsider]

Wasn't there something about Dex III and Dex VI shifting differently?

 

Yes, it is technically thinner, 5.8 cSt @ 100ºC vs 7.1. This could, theoretically, cause a change in shift quality in a more worn transmission. I've swapped between both and really didn't notice anything much.

 

The only "Dex/Merc" fluids that are guaranteed to conform to the old Dex III standards are those that are labelled as conforming with Allison TES-389. That standard was specifically created to mirror the old Dex III formulation for use in Allison transmissions that don't cope well with the thinner Dex VI fluid.

[Imp558]

I knew there was something, I always run the Walmart equivalent Dex III stuff. 

[Schurkey]

The only "Dex/Merc" fluids that are guaranteed to conform to the old Dex III standards are those that are labelled as conforming with Allison TES-389. That standard was specifically created to mirror the old Dex III formulation for use in Allison transmissions that don't cope well with the thinner Dex VI fluid.

Thanks for that.