Dex VI in older high mileage Chevy truck

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ATF is a subject I know little about, so bear with me, thanks.

My 2000 Chevy Silverado has 215K on the 5.3. It has had regular AT services, about every 50-60K miles (I drive mostly highway).

I had the AT serviced, and they put Dex-VI in it, assuring me it was the exact right choice. I understand its the latest GM fluid, and backward compatible. Is this OK? Thanks.
 
It's a better fluid no doubt, but when I put it in my high mileage Chevy that had always had DexIII the troubles started shortly thereafter. Not sure if it was related to the fluid but I won't do it again. That Chevy is now in the junkyard and our old Lumina will continue to get regular changes of DexIII.
 
Recognizing automatic transmissions are mysterious devices, I don't think you will have problems. The shop is correct, Dex-VI is backwards compatible with Dex-III. The physical differences among the two is the higher shear stability and lower viscosity of the newer fluid. Essentially that could translate to a different feel for clutch application, if that. Since you have been performing regular maintenance in your transmission, chances are you will not face any problems associated to the new improved fluid.
 
Originally Posted By: Tanama
Recognizing automatic transmissions are mysterious devices, I don't think you will have problems. The shop is correct, Dex-VI is backwards compatible with Dex-III. The physical differences among the two is the higher shear stability and lower viscosity of the newer fluid. Essentially that could translate to a different feel for clutch application, if that. Since you have been performing regular maintenance in your transmission, chances are you will not face any problems associated to the new improved fluid. ]


That in my opinion is what will make the difference in future longevity of an older transmission with the newer, backward compatible fluid.
 
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My company-owned work van, a 2001 GMC Safari, had the ATF changed with DexIII at 30,000 miles, at the dealer with Dex VI at 50,000, and at a small local repair chain, again with Dex VI, at 100,000. It now has 115,000 and the transmission is still just fine.
 
Quote:
Dex-VI is backwards compatible with Dex-III

In certain transmissions, not all that originally used Dex-III. All GM Hydramatic transmissions can switch to Dex-VI. Certain Allison transmissions, not all. Are there certain Aisin-Warner transmissions that are certified by A-W for Dex-VI? What else originally used Dex-III?
 
Originally Posted By: Ken2
In certain transmissions, not all that originally used Dex-III. All GM Hydramatic transmissions can switch to Dex-VI. Certain Allison transmissions, not all. Are there certain Aisin-Warner transmissions that are certified by A-W for Dex-VI? What else originally used Dex-III?


I know GM has stated the new Dex-VI is backwards compatible with Dex-III. Additionally, GM is out of the Dex-III licensing. As you stated, I've also read the Dex-VI might not be the best choice for certain Dex-III applications. Knowing there are a plethora of AFT's which claim compatibility or suitability for the old Dex II & III applications. But, what is the best choice for those old Dex specd transmission for which the new fluid is not recommended?
 
Originally Posted By: Tanama
Originally Posted By: Ken2
In certain transmissions, not all that originally used Dex-III. All GM Hydramatic transmissions can switch to Dex-VI. Certain Allison transmissions, not all. Are there certain Aisin-Warner transmissions that are certified by A-W for Dex-VI? What else originally used Dex-III?


I know GM has stated the new Dex-VI is backwards compatible with Dex-III. Additionally, GM is out of the Dex-III licensing. As you stated, I've also read the Dex-VI might not be the best choice for certain Dex-III applications. Knowing there are a plethora of AFT's which claim compatibility or suitability for the old Dex II & III applications. But, what is the best choice for those old Dex specd transmission for which the new fluid is not recommended?



1.) multi vehicle (dex/merc)?
 
How timely, I just changed my fluid in my 1989 Bonnevile, which I believe is the 440-T4 trans.

I used the Valvoline DEX/MERC as they say it meets DEX III specs. Would I have been better off with DEX VI?

Maybe a good idea to add some Lubegard Red?
 
The DexMerc is a fine product and is the original type used in your Bonny. No need for Lubegard.

Perhaps you may have been a little better off, but you can run the full interval on the fluid you did use. Just get Maxlife next time
smile.gif
 
Originally Posted By: tommygunn
The DexMerc is a fine product and is the original type used in your Bonny. No need for Lubegard.

Perhaps you may have been a little better off, but you can run the full interval on the fluid you did use. Just get Maxlife next time
smile.gif



Thanks Tommy.

I might do a short series of drain and fills to get rid of what was left over in the torque convertor. I won't need to replace the gasket each time will I? On the factor GM pan there is no drain plug so.
 
As far as replacing the gasket, it depends on how short the series is. If you drain it again after like 5k then you don't really need a new one.

Fortunately, you can probably get an aftermarket transmission pan that includes a drain plug, so future ATF changes are easier.
 
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