Issues with Dex VI

[ikle]

My GN has 50,000 original miles, the transmission is stock except for a Art Carr shift kit and Art Carr trany pan. Last winter I installed a PTC 10" 2800 stall converter and did a filter and fluid change. I used DexVI fluid, figuring with the higher heat range than Dex III, it would be the best choise for me. After a couple of months the firm shifts I had, had gotten a lot softer. What I am thinking, since Dex VI is the synthetic version of Dex III and are backwards compatiable, is change out the fluid in the trany pan with Castrols TransMax Dex/Merc and of course change the filter. I am hoping, by doing this, I will get my nice firm shifts back. What do you think. Thanks, Kyle

 

[kidglok]

Time for new clutches maybe?

 

[robzombie]

From what I've read and heard, dex Vl will soften your shifts but give you longer life.

Type F will give you firmer shifts but needs to be changed out more often [depends on driver abuse] at usually 10/15,000 miles.

Dex lll is in the middle of those above, and lasts longer than type F and shorter than dexVl.

Atleast that's what my trans guy tells me.

 

[Steve V]

I use dex VI and have no problem with nice firm shifts.

 

[696]

Just had Lonnie rebuild mine as well..Dex VI and shifts great.

 

[robzombie]

Just had Lonnie rebuild mine as well..Dex VI and shifts great.

I also have an EA trans and use dex VI and have firm shifts.

I never said it won't shift firm with dex VI, just that it would be firmer with type F.

What I posted was accurate and came straight from Lonnies mouth.

There is a difference in the fluids mentioned above and they will have characteristics that are unique to each of them.

 

[696]

Yep, used Type -F before the rebuild. Trying VI now to see how it does. Both are good.

 

[ikle]

Yep, used Type -F before the rebuild. Trying VI now to see how it does. Both are good.

I am thinking the reason why you have such great shifts is that your trany was rebuilt using parts and materials designed for Dex VI and mine has stock original parts and materials designed for Dex III. Now being that Dex VI is a synthetic version of Dex III the friction modifiers and or viscosity must be different allowing the trany to slip a little more than it did with the Dex III. So if I had nice firm shifts, in the past, with the old Dex III in theory if I drain the Dex VI out of the pan and replace it with Dex III it should dillute the Dex VI to the point were the firmness of my shifts should be restored,to some degree. I will have about 3 quarts of Dex VI, left in the converter, to about 8 fresh quarts of Dex III that my pan holds. Do you think this will work or am I missing something. Thanks, Kyle.

 

[Steve V]

Try doing a search on DexIV , specifically search Nick Micale's has post his write up about how it is way better than Type F, Dex III etc. I have gone from III to IV and had no issues at all.

IMO if you are having issue time to freshen the trans or return to "old school" tech

The rubber seals and friction components are not made for a specific fluid.

 

[robzombie]

Stay with one fluid.

I wouldn't cross contaminate fluids, you need to flush all the old fluid of one type out before changing to another.

 

[V6POWER]

Here are some comments by board members that I have copied/pasted over the years re: transmission fluids:


Nick Micale posted:

August 28th, 2009 04:53 PM​

Quote:
Originally Posted by SSedan64 (Post 2283123)
Some Info on Dexron VI.
The following chart represents the improvements over Dexron III.
Extended Fill Range = 100,000 miles Normal Use.
Change Interval = 50,000 miles Severe Use.
Clutch Friction Stability = Improved 100%
Clutch Durability = Improved 120%
Oil Film = Increased 20%
Fluid Oxidation = Improved 100%
Shear Stability = Improved 200%
Foam / Aeration= Improved 150%


I am done with Dexron III, Dexron/Mercon and Type F in any performance trans. For a few years we have tried various trans fluids.

Over a year ago we first tried Dexron VI in a 9 sec. build with a TH 400. We decided to pull the trans for a freshen after a full season of racing. The fluid looked brand new after draining, and all the wear parts looked new as well.

Just before the freshen job, we installed a race TH 400 in another 9 sec. GN. The first trip to the track the park bracket bolts came loose, but for 5 runs the trans was awesome. We had to pull the pan to tighten the bracket bolts, and glad we did. The Dexron III fluid was almost black.

These 2 cars, which are almost identical in build and track performance, finally gave us a valid basis of comparison that we have been wanting..

Moral of this story is that we will only use Dexron VI or similar in any performance build. The extra heat from high stall converters and a trans brake kills regular fluid in a very short time. The data above also point this out.

Another similar 9 sec. GN is currently using hydraulic fluid, so when we start racing again next month, we want to see how that compares to the synthetics.

Also, I am sorry this is off-topic from the original post, but thought it might be of some value. :redface:
-------------------------------------------------------------------------------------------------------


bison posted:

April 21st, 2010 05:42 PM​

Dex 6. Takes heat like a champ. Type F is crap if it’s going to get over 200*. It won’t last. No problem if your going to be changing it all the time
-----------------------------------------------------------------------------------------------------


Renthorin posted:

June 2nd, 2010 08:30 AM​

Can I mix dex3 and dex 6?

going to change the filter and fluid in the pan and am reading some good things about Dex 6 synthetic fluid.

I won't be able to get all the fluid in there now out so if I switch to 6 it will become a mixture of the two.

Is that ok?

Will

mikey1107 posted:

June 3rd, 2010 01:21 PM​

According to GM, yes it can.

This is from a GM bulletin

The use of Dexron VI in place of Dexron III.

Recommendation/Instructions:
Dexron VI can be used in any proportion in past model vehicle equipped with a automatic transmission/transaxle in place of Dexron III i.e. topping off the fluid in the event of a repair or fluid change. Dexron VI is also compatible with any former version of Dexron for use in automatic transmissions/transaxles.

Dexron III must not be used in place of Dexron VI in models that specifically call for the use of Dexron VI, fluid and component life will be compromised.

DO NOT use Dexron VI in place of CVT fluid or in any component that does not specifically call for the use of Dexron III (or any former version of Dexron).

 

[ikle]

Here are some comments by board members that I have copied/pasted over the years re: transmission fluids:


Nick Micale posted:

August 28th, 2009 04:53 PM​

Quote:
Originally Posted by SSedan64 (Post 2283123)
Some Info on Dexron VI.
The following chart represents the improvements over Dexron III.
Extended Fill Range = 100,000 miles Normal Use.
Change Interval = 50,000 miles Severe Use.
Clutch Friction Stability = Improved 100%
Clutch Durability = Improved 120%
Oil Film = Increased 20%
Fluid Oxidation = Improved 100%
Shear Stability = Improved 200%
Foam / Aeration= Improved 150%


I am done with Dexron III, Dexron/Mercon and Type F in any performance trans. For a few years we have tried various trans fluids.

Over a year ago we first tried Dexron VI in a 9 sec. build with a TH 400. We decided to pull the trans for a freshen after a full season of racing. The fluid looked brand new after draining, and all the wear parts looked new as well.

Just before the freshen job, we installed a race TH 400 in another 9 sec. GN. The first trip to the track the park bracket bolts came loose, but for 5 runs the trans was awesome. We had to pull the pan to tighten the bracket bolts, and glad we did. The Dexron III fluid was almost black.

These 2 cars, which are almost identical in build and track performance, finally gave us a valid basis of comparison that we have been wanting..

Moral of this story is that we will only use Dexron VI or similar in any performance build. The extra heat from high stall converters and a trans brake kills regular fluid in a very short time. The data above also point this out.

Another similar 9 sec. GN is currently using hydraulic fluid, so when we start racing again next month, we want to see how that compares to the synthetics.

Also, I am sorry this is off-topic from the original post, but thought it might be of some value. :redface:
-------------------------------------------------------------------------------------------------------


bison posted:

April 21st, 2010 05:42 PM​

Dex 6. Takes heat like a champ. Type F is crap if it’s going to get over 200*. It won’t last. No problem if your going to be changing it all the time
-----------------------------------------------------------------------------------------------------


Renthorin posted:

June 2nd, 2010 08:30 AM​

Can I mix dex3 and dex 6?

going to change the filter and fluid in the pan and am reading some good things about Dex 6 synthetic fluid.

I won't be able to get all the fluid in there now out so if I switch to 6 it will become a mixture of the two.

Is that ok?

Will

mikey1107 posted:

June 3rd, 2010 01:21 PM​

According to GM, yes it can.

This is from a GM bulletin

The use of Dexron VI in place of Dexron III.

Recommendation/Instructions:
Dexron VI can be used in any proportion in past model vehicle equipped with a automatic transmission/transaxle in place of Dexron III i.e. topping off the fluid in the event of a repair or fluid change. Dexron VI is also compatible with any former version of Dexron for use in automatic transmissions/transaxles.

Dexron III must not be used in place of Dexron VI in models that specifically call for the use of Dexron VI, fluid and component life will be compromised.

DO NOT use Dexron VI in place of CVT fluid or in any component that does not specifically call for the use of Dexron III (or any former version of Dexron).

Good info, but like GM states, Dex VI and Dex III are compatible you just can't use Dex III in a trany calling for Dex VI but you can use Dex VI in a trany calling for Dex III. So it should be no problem mixing the two together. Nick Macale states he uses Dex VI in any " performance " trany, in my opinion a stock trany isn't a performance trany. When I have mine rebuilt I will be using high quality parts and using Dex VI. But in the mean time I am going back to Dex III to see if it makes any difference. I am going to call Nick tomorrow to verify what I plan on doing. Thanks Again, Kyle.