Confused on Dex-VI

[sciphi]

Standing in Wally's tonight waiting for my tires to be put on, I was reading the backs of the ATF containers, since I'm changing the ATF on my 1999 Buick LeSabre shortly.

All the bottles marked "Multi-Vehicle Formula" said they were suitable replacements for Dex-III, and to be used in any unit that called for Dex-III, and not to use in any unit that called for Dex-VI.

I've heard that GM made Dex-VI the recommended ATF for all their units that formerly specified Dex-III. Doesn't that make all those Dex-III-compatible fluids superfluous, since GM changed the spec on all their transmissions to Dex-VI?

 

[JohnBrowning]

I recently changed the fluid in my wifes 1997 Buick LaSaber and used Walmart's High Milage ATF and so far so good!

 

[umungus1122]

The dex-3 compatible fluids can be made and sold at a lower price point, garnering sales from those who don't want/need the more costly dex-6.

 

[dwendt44]

Correct. Dex-VI is a semi-synthetic blend.
When I changed T fluid in my 05, I went with Mobil-1 synthetic T fluid. Pan drop w/filter change.
Work fine.
Supposedly, the Dex-6 is backward compatible with Dex 3; meaning that you can add/mix the 6 with 3 but it's not recommended to add 3 to a transmission that has 6 in it.
Is that as confusing as it sounds?

 

[Whitewolf]

DEXRON-VI is generally Gp III although the spec does not preclude the use of PAO/Ester base combinations. The confusion arises because in the USA group III stocks can be labelled as synthetic.
Yes DEXRON-VI was designed to be backward compatable so it can be used in all Hydramatic transmisions that called for DEXRON-III or earlier DEXRON specifications. Try not to mix DEXRON-III with DEXRON-VI, only because if you do that you are in fact diluting the DEXRON-VI fluid with a less stable product and therefore throwing away much of the advantage. All you need to remember is that DEXRON-VI is far superior to DEXRON-III and also that DEXRON-III no longer 'exists' in terms of licensing so there's no control over the formulations (if you go out and buy a 'DEXRON-III' fluid in reality you have no idea what you're paying for!). In contrast, GM controls the formulations for DEXRON-VI licensed products ... so you know exactly what you're buying.

 

[onion]

Whitewolf- what do you think about running DexVI in a non-GM transmission that originally specified DexIII?

What I have in mind are Allison transmissions in medium/heavy trucks, busses, etc. Allison is sending at least some of their new transmissions out with DexVI these days (the ones in chevy/GMC trucks), while the rest take Transynd. They have a bulletin out saying not to use DexVI in older Allisons because there are potential seal compatibility problems.

Your thoughts?

 

[Whitewolf]

I'll PM you.

 

[SMB]

Originally Posted By: onion
Whitewolf- what do you think about running DexVI in a non-GM transmission that originally specified DexIII?



I would like to know as well, since my Toyota requires DexIII.

 

[jaj]

Originally Posted By: Whitewolf
I'll PM you.


Would you PM me too please?

I've got a Mercedes Benz 722.3 transmission that takes Dex III. I buy it from the MB dealership - MB Canada has a deal with Shell so they sell QS Dex IIIh, or at least they did the last time I was there two years ago. This is a gearbox that has a drain on the torque converter so it gets a pretty complete change when you drain it.

I'm wondering if Dex VI is what goes in next or if I have to invest in the latest MB-branded fluid that's backward compatible and twice the price.

 

[Big O Dave]

So, if a vehicle is spec'd for Mercon-Dexron III, then Dex VI is okay? For example, my '95 Ford Explorer with a 4R55E...

 

[The Critic]

Originally Posted By: Big O Dave
So, if a vehicle is spec'd for Mercon-Dexron III, then Dex VI is okay? For example, my '95 Ford Explorer with a 4R55E...

If the vehicle previously called for Mercon, Ford recommends that you use Mercon V.

 

[Big O Dave]

I know, but I was asking if I can use Dex VI, since Mercon = Dex III, and Dex VI is superseding all Dex III applications.

Maybe I answered my own question...

 

[PT1]

I have DexVI in my 2006 Yukon 4L60e and it shifts way better than the DexIII did in my 02 and 99 4L60E trucks. Not my imagination as the test for me is cold Winter start up operation. The DexIII would seem to delay shifting while the DexVI is crisp & robust right away so you can really feel the difference. I'm fairly certain this is due to cold flow characteristics of the 2 very different fluids.

 

[unDummy]

I've got 2 Fords running DexronVI. Neither have blown up yet.
Since I'm on an MPG fix, I will soon be dumping ATF+4 in my Toyota for DexronVI(or D6).

Instead of PM'ing answers, why not just answer the question here.

Allison has a SN range for DexronVI in GM products.

DexronVI in every NON-GM is a risk that you take. Will it work? most likely? could you have an issue? maybe! Worth the risk, why not!

 

[Big Jim]

Originally Posted By: Big O Dave
So, if a vehicle is spec'd for Mercon-Dexron III, then Dex VI is okay? For example, my '95 Ford Explorer with a 4R55E...

Good question. There is a guy on Escape Central that is running Dex VI in his Escape. He likes it.

 

[Whitewolf]

Well I think that you answered your own question. Would it work that way round, probably. Is there a risk? Yes but not as big as if you were proposing to substitute say +4 for DEXRON-VI.

 

[sciphi]

Okay, so should I have the dealer flush the 4T65-E (?) unit in my 1999 LeSabre or do a series of pan drops that will remove about half the fluid per drop? I'm ruling out other places than the dealer because they will most likely use whatever bulk ATF they have on hand instead of the dealer's bulk Dex-VI.

 

[Donald]

Why not do a cooling line flush yourself. Its the most cost effective and you will be 100% positive about what fluid is in your tranny. Not any harder than a few a few pan drops and a lot easier if you do not have a drain plug. The problem with a drain & refill (example 50% ATF change/refill) is that when you get to your 4th drain and refill, yo are dumping 87% new ATF to get to 93 percent new ATF.

If you use synthetic ATF, its really a bad way of doing it cost wise. Basically as the cost of the ATF goes up it becomes a worse and worse way to swap all the old fluid.

From an environmental viewpoint its really bad.

I think a drain and refill is a great way to "refresh" the ATF every 15K-20K miles, but a bad way to swap out all the old fluid.

 

[sciphi]

Okay. I'll see if I can't shanghai a few friends into doing this with me now that it's nice out.

One to crank, one to catch the old fluid, one to dump the new fluid and yell "stop!".

 

[Big Jim]

It works well with just two people, one person watching the outgoing fluid while adding fluid with a second person switching the engine on and off.

Once you are accustomed to it, one person can handle it.

Catch the old fluid in a 5 gallon plastic bucket. It helps if you calibrate the bucket ahead of time. Add water to an empty bucket one quart at a time and mark the height of the column with each quart. This makes it easier to tell how much you have pumped out.