Stay with Dexron 3 or go with Dexron 6

[229]

Originally Posted By: WishIhadatruck
My 1996 4L60E trans in my Buick was switched to Dex VI long ago and it seems to love it.

My 2001 4T65E in my Grand Prix seemed fine at first but I'm questioning if some of my problems are related or not. I ran Dex III (M1) for the first 90k miles and I'm nearly done with the next 90k miles of using Dex VI. I think I'll try Redline D4 next time. My TC can't always decide if it wants to lock up and I've also had issues with harsh shifting due to a solenoid issue that was resolved mostly by a shift kit. Both of those issues are common with this trans and most likely are not fluid related but I'm going to try something different next time. The M1 was severely sheared down in the 5.x range so I can't believe a thinner Dex VI would be much different if more shear resistant than the M1 Dex III. The new VI is thicker than the old M1.

I will continue to use the Dex VI in my wagon with the 4L60E.


Stay with what you have been using as most of us have not gotten that much mileage before a rebuild on that particular model.

 

[fpracha]

Originally Posted By: Thax
Stay with Dexron III , it is what the trans was designed on. I have see several customer complaints of shift problems going from Dexron III to VI. I would suggest using Valvoline Maxlife Dex/Merc.

Please explain what types of "shifting problems" did those customers experience? Thanks.

 

[Ken2]

Quote:
There is not a single licensed DIII product on the market.
Not exactly. Allison TES-389 fluid is Dexron-III(H) under another name. If the fluid you buy says that it is recommended for Dex-III usages and qualified for TES-389, you got the real stuff. Mobil D/M ATF is just one; there are others.

And, yes, Dex-III and Dex-VI mix OK. There is no way to avoid mixing them in a transmission unless you take it apart and wipe it dry.

 

[KCJeep]

Originally Posted By: Thax
Stay with Dexron III , it is what the trans was designed on. I have see several customer complaints of shift problems going from Dexron III to VI. I would suggest using Valvoline Maxlife Dex/Merc.


+1

Within a month or two of switching our Venture over to Dex VI the trouble started. I'd suggest a quality Dex/Merc and two bottles of Lubegard Red instead.

 

[ET16]

Originally Posted By: 229
Originally Posted By: Bluestream
I would go with Mercon V just to be safe...Who wants to have to drain out good ATF if its doesn't work well.

He means Dexron VI.

There is not a single licensed DIII product on the market. You may get a wide range of qualities.


I think Mercon V wouldn't be so bad. It's better than Dex III and it seems to be thicker than Dex VI.

 

[Boss302fan]

Maxlife ATF and a new ATF filter with two bottles of LG Red. If this does not help within 1K miles then you have mech issues... Good luck.

 

[94astro]

Thanks to all, I have read all your posts & now trying to figure out my best approach. After much studying and research & all of your input I think here is what I will do: drop the pan & change the filter then fill with Dex3 and a bottle of Lubegard Red, after a couple thousand miles repeat but with Maxlife Dex/Merc. My Astro van only has 67K so there shouldnt be too much wear involved as it has never been abused, used to tow or loaded at all. Well, if you have any input about my plans please reply & again I thank you all.

 

[jlmwyo]

Originally Posted By: Ken2
Quote:
There is not a single licensed DIII product on the market.
Not exactly. Allison TES-389 fluid is Dexron-III(H) under another name. If the fluid you buy says that it is recommended for Dex-III usages and qualified for TES-389, you got the real stuff. Mobil D/M ATF is just one; there are others.

And, yes, Dex-III and Dex-VI mix OK. There is no way to avoid mixing them in a transmission unless you take it apart and wipe it dry.


I had this very same question as well. Well, HAVE still. I did a pan drop/filter and fluid exchange today with Valvoline Dex/Merc. This is in a 1989 Bonny with a 440-T4 trans.

I found a handy spreadsheet somewhere on this site that will show you how many exchanges you have to do to get basically 'clean' and new fluid. If I do ONE more 6 quart exchange my fluid will be basically 85 percent new.

Should I stick with the Valvoline Dex/Merc?

Who besides Mobil makes TES-389 fluid? It wasn't clear to me from looking at Mobil's site that it actually MEETS Dex-III spec just that it was 'equivalent'. Which is what Valvoline says about it's Dex/Merc.

Speaking of said fluid:

http://www.pqiamerica.com/ATF Feb 2012/Valvoline ATF.htm

It looks pretty dang good if all you want to do is meet the Dex III spec. The FSM calls for DEX II

 

[Bgallagher]

Originally Posted By: Warstud
DexIII & Lubegard...


+1 My Malibu didn't shift as nicely when I flushed it with D-VI versus D-III. Flushed it again with supertech D-III and it shifts beautifully. LGR made it shift even more crisp. Not lazy but crisp and comfortable.