: Dexron III Or Dexron VI



SDCaddyLacky
04-21-11, 04:17 AM
To the ones that have poured in Dexron VI instead of the old Dexron in your Cads. Have you experienced any improvements in your shift quality? Or no?

If so, did you notice any changes like firmer shifts or softer ones?

This goes for all 80-96 Fleetwood and Brougham owners.

outsider
04-21-11, 07:19 AM
i actually use the stuff at walmart that says it replaces dexron and mercron...

works fine. no adverse affects.

sven914
04-21-11, 05:16 PM
Dexron VI is completely compatible with any other Dexron that came before it.

RippyPartsDept
04-21-11, 05:27 PM
:yeah:

except for in like one or two manual transmission applications (but that doesn't affect anyone on this site)

SDCaddyLacky
04-21-11, 07:17 PM
I know Dexron VI is compatible with our Caddys, I was asking if anyone that used the newer Dexron saw any improvements in their shift quality and if so, do you think it's worth the extra cash to put in the trans.

sven914
04-21-11, 07:47 PM
Upgrading the fluid wont improve the shift quality (above the natural benefits of new fluid). It depends heavily on how bad the transmission is currently functioning, if new fluid will do anything. If you are experiencing problems with it slipping or having hard or late shifts then there may be a mechanical issue.

brougham
04-21-11, 09:23 PM
You can use a completely different kind of transmission fluid that can make the transmission feel different but it could also cause problems. Fluid from the same family like dexron won't make much of a difference.

N0DIH
04-22-11, 11:25 AM
I switched it in my 00 Park Ave Ultra, can I say it make a big difference? No, but it seems more consistent when over temp extremes (hot or cold), but no dramatic difference.
Seeing the specs on Dexron VI vs IIE/III, I would go with VI. Or go with Amsoil Torque Drive. That is what I would prefer to have in there...

C66 Racing
04-22-11, 12:21 PM
I switched it in my 00 Park Ave Ultra, can I say it make a big difference? No, but it seems more consistent when over temp extremes (hot or cold), but no dramatic difference.
Seeing the specs on Dexron VI vs IIE/III, I would go with VI. Or go with Amsoil Torque Drive. That is what I would prefer to have in there...

The biggest difference between Dexron VI specification and Dexron III is that the viscosity of the VI is about 40% lower than that of the III (which helps GM improve their CAFE). The requirements for performance of the VI probably require at least a semi-synthetic blend, but the basestock is not specified so some offerings of VI can use better or probably worse basestocks. The performance requirements of the III allowed mineral oil to meet them, though many offerings such as the AMSOIL Torque Drive mentioned by N0DIH use a Group IV synthetic PAO basestock. Personally, in my vehicles which specify a Dexron III, I use a good Dexron III fluid like N0DIH mentioned vice taking the lower viscosity of the VI.

For those interested in using a fluid with a better basestock as mentioned by N0DIH, for automatic trannies, AMSOIL's recommendation for Dexron III:
AMSOIL Universal ATF (http://www.c66racing-synthetics.com/Product%20Bulletins/ATFPB.htm) (Product Code ATFQT)
AMSOIL Torque-Drive Synthetic Transmission Fluid (http://www.c66racing-synthetics.com/Product%20Bulletins/ATDPB.htm) (Product Code ATD1G)
For Dexron VI:
AMSOIL Low Viscosity Universal Automatic Transmission Fluid (ATL) (http://www.c66racing-synthetics.com/Product%20Bulletins/ATLPB.htm) (Product Code ATLQT)

For those desiring to try the AMSOIL, I'm more than happy to get it for you at dealer wholesale, about 25% below retail, via the AMSOIL Preferred Customer Program (http://www.c66racing-synthetics.com/Preferredcustomer.htm). Drop me a PM if interested.
:cheers:

johnny kannapo
04-22-11, 01:14 PM
It can't be denied the Dex3 born transmissions hold up very well under normal use. The cost difference is a major consideration in that the Dex6 choices are 3 or 4 times the cost & more. When Valvoline Merc/Dex3 is availiable a WM for under $3 a qt., it doesn't make sense to throw around to $200 just for the ATF.

The Dex3 I flushed out at 100,000mi looked worthy of going another 100,000.

Unless you tow or other hard use, I'm not seeing the need.

N0DIH
04-22-11, 01:25 PM
A friend mine points out that the Dexron IIE/III spec'd oil for our cars has been around for a long time and why are we so smart to "improve" on it? My point is GM didn't change the trans and did the oil and seeing the datasheets on the oils, VI was much improved. I think it is worth it, but I don't like thin oils either..... So III is very much hard to beat.

intragration
04-23-11, 02:51 PM
Sven, I've heard that people have upgraded to Dex VI for improved performance, and experience "better" shifts. I believe this was in regard to Northstar cars. I don't know if the same would apply to our older transmissions, and I didn't look into it because it's not that important to me, but the possibility exists. I personally agree with the mindset that if it's working, don't fix it.

N0DIH
04-23-11, 03:33 PM
In the north here, thinner oil is welcome for the cold days....

sven914
04-23-11, 04:05 PM
Sven, I've heard that people have upgraded to Dex VI for improved performance, and experience "better" shifts. I believe this was in regard to Northstar cars. I don't know if the same would apply to our older transmissions, and I didn't look into it because it's not that important to me, but the possibility exists. I personally agree with the mindset that if it's working, don't fix it.

Their transmission was probably in need of service. If they replaced the fluid with new Dex V or III or whatever was factory, they would have experienced the same thing.

N0DIH
04-23-11, 05:48 PM
I still often run some 30W engine oil in with my trans. Some say that is so bad, but reality is my 91 Bonneville went 275k miles with a pretty high amount of synthetic engine oil in it. I was probably running around 50% Mobil 1 engine oil/Amsoil ATF in it.

Why? thicker oil, the RV guys started doing that with the old THM400's and C6's to give a better lockup, and it also made the trans run cooler. Trans Fluid is only like 5w or 10w engine oil with a ton of detergents and friction modifiers.

Changing it often (30k miles or so) is best to make a trans last and to not abuse.... ESPECIALLY fwd where the diff shares the trans lubricating system.

johnny kannapo
05-03-11, 04:08 PM
A friend mine points out that the Dexron IIE/III spec'd oil for our cars has been around for a long time and why are we so smart to "improve" on it? My point is GM didn't change the trans and did the oil and seeing the datasheets on the oils, VI was much improved. I think it is worth it, but I don't like thin oils either..... So III is very much hard to beat.

I am not contesting the worthiness of VI, I agree it is a superior oil with current chemistry & is worth every penny. An excellent ATF.

I question how necessary is it to switch when Dex III performs so well & goes the lifetime of the car in some many cases.

My point is doing the oil change service will save you about $120 for the ATF price difference.

The benefits of Dex VI are not even measurable other than the price.