Improvements in DexronVI over DexronIII

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MolaKule

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For DexVI, the friction modifier, metal deactivator and antioxidant chemistry's are more stable over a longer time duration.

What this does not mean is the level of additives is higher.

What this does mean is that the shifting performance and overall performance of the fluid will last longer, assuming no internal mechanical or hydraulic problems develop in the transmission.

Improved Metal inhibitors further keep the oil from oxidizing and forming varnishes.


DexVI is also much improved in the area of shear stability.

For a mineral-based Dexron III, the fluid may start out at 7.5 cST and shear down to 4.5 cSt within 30k miles.

For DexronVI, the fluid starts out at 6.0 cSt and may shear down to say 5.7 cSt.

The reason for the improved shear stability is due to two pieces of chemistry:

1. Some formulators use improved and highly stable VII polymers;
2. others use the new HM polymer esters not considered as VII chemistry.

As far as detergency, approximately the same amount of detergent chemistry is available in DexronVI as in DexronIII.

One of the reasons some manufacturers describe their DexronVI's as synthetic blends is that the DexronVI base oils are a mix of GroupIII, IV, and V oils.

The newer friction modifiers are not more "slippery." They have about the same friction coefficients as previous fluids, but are simply more stable over the life of the fluid.
 
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In ATF applications requiring older Dexron fluids, DexronVI should be backward compatible, unless the manufacturer explicitly forbids the DexronVI.
 
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Excellent information, thanks. The improved/greater shear stability data appears to correspond to the point made by Ashland in it's response to the recent PQIA-MaxLife Dex/Merc ATF advisory controversy.
 
Originally Posted By: sayjac
Excellent information, thanks. The improved/greater shear stability data appears to correspond to the point made by Ashland in it's response to the recent PQIA-MaxLife Dex/Merc ATF advisory controversy.


Exactly.
 
Most ATF's are dyed red but the color can fade over time.

My Chevy's dipstick has low and high level marks but it is difficult at times to verify the level.

In my case I have to verify levels when the engine is running and engine, coolant, and fluid is hot.

I pull the stick and immediately orient it horizontally to read the level, wipe the stick, and then do this two more times and take an average.
 
It looks like the swipe of an oil stick after a fresh fill with M1. Clear, almost invisible, a little tan. Unlike my other cars which are varying shades of red. Maybe thats why I clunk going into gear, it looks clear cause there's nothing on the stick.
shocked.gif
 
Thanks MoleKule!! I was just about to change the avalanche, and was debating DEX III or DEX VI The VI it will be!
 
Originally Posted By: MolaKule
In ATF applications requiring older Dexron fluids, DexronVI should be backward compatible, unless the manufacturer explicitly forbids the DexronVI.


GM has stated not to use Dex VI in place of Dex III type fluids in MTs. Any idea why?

Also, what's the deal with elastomer compatibility in old ATs? I believe Allison isn't back-specing this because of compatibility...
 
Thanks for clearing up the synthetic blend part! I was thinking blends were conventional/synthetic. Never in my dreams did it occur to me that blend could mean a mix of III,IV, or V!
 
Originally Posted By: JHZR2
Originally Posted By: MolaKule
In ATF applications requiring older Dexron fluids, DexronVI should be backward compatible, unless the manufacturer explicitly forbids the DexronVI.


GM has stated not to use Dex VI in place of Dex III type fluids in MTs. Any idea why?


Search for "SRT4 Transmissions Ed Peters" on Youtube and you'll get an interesting insight in the OEM's view of transmission fluids. Ed was a driveline engineer at Chrysler before he retired. Ed's explanation for using ATF in manual gearboxes was that it saved a lot of money on the fill line in the factory because they didn't need a separate set of equipment to fill manual transmissions - they just put ATF in everything.

He has some interesting points on what makes a good gear oil and why, from a transmission engineer's standpoint.
 
Originally Posted by JHZR2
Originally Posted by MolaKule
In ATF applications requiring older Dexron fluids, DexronVI should be backward compatible, unless the manufacturer explicitly forbids the DexronVI.


GM has stated not to use Dex VI in place of Dex III type fluids in MTs. Any idea why?

Also, what's the deal with elastomer compatibility in old ATs? I believe Allison isn't back-specing this because of compatibility...


I would prefer to defer the answer until I speak with Mr. Johnson at the next STLE meeting for clarification.
 
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Originally Posted By: jaj
Originally Posted By: JHZR2
Originally Posted By: MolaKule
In ATF applications requiring older Dexron fluids, DexronVI should be backward compatible, unless the manufacturer explicitly forbids the DexronVI.


GM has stated not to use Dex VI in place of Dex III type fluids in MTs. Any idea why?


Search for "SRT4 Transmissions Ed Peters" on Youtube and you'll get an interesting insight in the OEM's view of transmission fluids. Ed was a driveline engineer at Chrysler before he retired. Ed's explanation for using ATF in manual gearboxes was that it saved a lot of money on the fill line in the factory because they didn't need a separate set of equipment to fill manual transmissions - they just put ATF in everything.

He has some interesting points on what makes a good gear oil and why, from a transmission engineer's standpoint.


Ill have a look. THat is plausible, but a less viscous fluid will cause less drag and offer a smother feel, potentially, at least in boxes that need it.

Im looking forward to Mola's comments.
 
Originally Posted By: JHZR2
Originally Posted By: MolaKule
In ATF applications requiring older Dexron fluids, DexronVI should be backward compatible, unless the manufacturer explicitly forbids the DexronVI.


GM has stated not to use Dex VI in place of Dex III type fluids in MTs. Any idea why?

Also, what's the deal with elastomer compatibility in old ATs? I believe Allison isn't back-specing this because of compatibility...


Found this, may help answer..

http://www.hollonoil.com/PDF/DEXRON-VI-Service_Fill_Release.pdf
 
Originally Posted By: MolaKule
In ATF applications requiring older Dexron fluids, DexronVI should be backward compatible, unless the manufacturer explicitly forbids the DexronVI.


I have put it in older units in street cars (TH350, 4L80E) and it performs flawlessly.

I have heard of it causing issues for some folks, though I can't imagine why. We love this stuff.
 
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I have heard of it causing issues for some folks, though I can't imagine why.


Me neither.

The problem I see with some of the "DexronVI caused such as such problem" statements is the lack of a clear, definitive cause-and-effect relationship.

In many cases, some guy finally checks his ATF and discovers it has never been changed, it looks like 100,000 mile diesel oil, and tries to clean up a tranny not shifting properly and most likely on its way out.
 
Well i am one of those guys that have had issues with dex 6. It was in an 02 blazer that my wife and i bought new. I live around GSO NC so we dont have alot of mountains or anything. My wife primarily drove the blazer to and from work. We also traveled in it so there was a good bit of highway miles on it. Anyway the service history is as follows:

22K - fluid and filter RR with factory fluid
36K - fluid and filter RR with M1 ATF
80K - fluid and filter RR with advance auto brand fluid
115K- fluid and filter RR with M1 ATF
163K- fluid and filter RR with Valvoline Dex6

When draining the M1 out, it looked almost new and i questioned why i change it so often but went ahead with my plan being i bought a case of the DEX 6. I was convinced it was fine. At 183 K miles i have a note in my maintenance log that the transmission fluid looked burnt looking as well as slightly burnt smell. I thought maybe the dex 6 was just cleaning something up or what ever and decided to drive it a bit longer. At 193K miles the fluid was getting worst and i felt like it was slipping a bit ( maybe just panic setting in). I installed a drain plug on the pan and did three drain and fills with WM ST DEX3 until the fluid was nice and red. It now has 215K on it now and the fluid is still looking new.

I dont understand why this happened. The only conclusion i came to is that the fluid is slightly different and maybe my tranny is a little old or the spring are weak but it did not appear to like the Valvoline DEX6.

Just one guys experience. This is a great post because as a engineer, i would really like to understand how this happened or what the root cause was. I know that for the rest of the blazers life it will get ST dEX3 at 30K intervals.
 
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i have a note in my maintenance log that the transmission fluid looked burnt looking as well as slightly burnt smell. I thought maybe the dex 6 was just cleaning something up or what ever and decided to drive it a bit longer. At 193K miles the fluid was getting worst and i felt like it was slipping a bit ( maybe just panic setting in).


Since you still had about half Mobil 1 ATF I don't see how you can attribute a cause to the other fluid, Valvoline D6.

If anything, the inference is the Valvoline D6 was cleaning out crud that others had not been able to clean.

Now had you done three straight drain and refills with Valvoline D6 ATF and this occurred, Then I could see a weak cause and effect.

And this was Valvoline D6 and not Maxlife?
 
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Originally Posted By: MolaKule
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i have a note in my maintenance log that the transmission fluid looked burnt looking as well as slightly burnt smell. I thought maybe the dex 6 was just cleaning something up or what ever and decided to drive it a bit longer. At 193K miles the fluid was getting worst and i felt like it was slipping a bit ( maybe just panic setting in).


Since you still had about half Mobil 1 ATF I don't see how you can attribute a cause to the other fluid, Valvoline D6.

If anything, the inference is the Valvoline D6 was cleaning out crud that others had not been able to clean.

Now had you done three straight drain and refills with Valvoline D6 ATF and this occurred, Then I could see a weak cause and effect.

And this was Valvoline D6 and not Maxlife?


I see what your saying about the M1 but it has been in there at least part of the time since early on. If the M1 was causing the issue, the fluid would be bad when i drained it to add the D6. Your right, the Valvoline could have been cleaning up what the others had not but i really dont think so. It really started to have a burnt smell but I guess it could be possible. Also the M1 looked perfectly fine when i drained it and added the dex6. Really dont make sense to me.

Just thinking about it, maybe it was a mixture of the fluids that it didn't like. Not sure exactly the cause but im pretty convinced something happened with the dex 6 change that the tranny didn't like. As often as i changed it and as good as the fluid always looked, i personally dont think there was that much gunk in there to cause my fluid to look as bad as it did along with the smell.

I agree that dex 6 is supposed to be completely backward compatible and i did a lot of research on it before i bought a entire case of it. At the time it was about 70 dollars.

To answer your question, this was regular Valvoline D6 in the blue bottle. Definitely not Max Life.
 
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