Dextron III / IV or Synthetic ATF
 

Corrected Post to Dexron...thanks!


Just bought another PerformaBuilt Trans from Alan Pickering.
Got their Heavy Duty 4L60E Truck version for the 94 Caprice Wagon.
Planning adding a 383 as the current engine has 250,000 miles.
This will complete the powertrain restoration.

Alan recommended any Dexron III or IV and Synthetic is ok.
Going to add a second cooler.

My question.
Does Synthetic AFT offer any advantage over Dexron?
Researching over the internet there is a lot of antidotal information.
Nothing is clear as to which is better for Towing.
Except Synthetic is a lot more expensive.

Looking at the Ounce of Prevention = Pound of Cure.
If it exists in this case.

Need some help.

Dan

Re: Dextron III / IV or Synthetic ATF
 

I believe that quality synthetics offer an extra level of protection all-around, but mainly from their resistance to heat degradation. Heat is usually cited as the #1 contributor to transmission failures. I use the appropriate Amsoil synthetics in my race trans and pull it every 3-5 years years, not because of problems, but just as preventive maintenance. I bracket race and run association events as well as IHRA. My trans builder says to keep using/doing what I have been. I figure that trans brake and towing applications have more to gain from it than footbraking.

Re: Dextron III / IV or Synthetic ATF
 

Dextron is a copyright owned by GM . If the bottle of ATF says Dextron then it meets the GM specs for that Dextron fluid . They are tested and approved by GM . The later versions of Dextron which is now Dex6 , is able to service earlier versions of Dextron . So there are companies that make synthetic versions of Dextron , and they offer all the benefits of synthetic oils . Also the fluid that is specified for Allison automatics is called TransMax and is synthetic . It is a very high quality fluid that meets Dextron specs and is made by Castrol .

Re: Dextron III / IV or Synthetic ATF
 

It is actually DEXRON not DEXTRON as the original poster stated. Dextron is a veterinary medicine.Sorry just a pet peeve of mine after being a parts man for over 30 years !

Re: Dextron III / IV or Synthetic ATF
 

Darn auto correction feature !

Re: Dextron III / IV or Synthetic ATF
 

Synthetic VS conventional oil results in a 20 degree cooler temp in a street driven ENGINE (should be same in a trans? friction is friction).
My findings with oil temp guage on Jeep 4.0 engine.

Re: Dextron III / IV or Synthetic ATF
 

Last year was very hot and towing up the Appalachian mountains was a real adventure.
I lost a transmission towing home from one race.
Only two miles from home.

Dexron ATF is sold under different brands.
Do these vendors make their own blends to meet Dexron specifications?

Is there an advantage of using a Dexron Synthetic over GM Dexron or one of its competitors?

Do any of the companies have a version of Dexron for heavy duty towing?

D

Re: Dextron III / IV or Synthetic ATF
 

Don't forget a huge trans cooler to plus the type and location so important too

Re: Dextron III / IV or Synthetic ATF
 

Dexron is licensed by G.M. Apparently to sell any dexron product the manufacturer must submit the blend and contents to G.M. for approval. From what I've read G.M. no longer monitors anything prior to dexron VI as dexron 6 supersedes all other dexron fluids.
I agree with Myron that the synthetics offer more protection against heat. The only draw back I've heard of is that in a high horsepower combination, the synthetic is so slick that it can allow the clutch plates to slip.If you plan to do a lot of towing I'd use the synthetic.

Re: Dextron III / IV or Synthetic ATF
 

Dexron 6 is a synthetic and is usually reasonably priced and works great in modern and older transmissions.

Re: Dextron III / IV or Synthetic ATF
 

While there may be synthetic versions of Dex6 , the factory fill is not synthetic . The additive package that is in Dex6 defines the anti-wear , foaming , and friction characteristics. Dex6 synthetic or Dex6 mineral based fluid will have the same friction profiles . That is the definition of Dex6 .

Re: Dextron III / IV or Synthetic ATF
 

Dexron HP fluid, which is what GM is now using in the 8 speeds is fully synthetic. Some of the the 8 speeds that were filled with Dex6 are having tcc shudder issues and they are having us flush and refill with the HP fluid. I fixed a very low mileage 17 Canyon with this procedure. The GM part number is 19300536. Mobil 1 also has a version. Stuff is pretty pricey though.

Re: Dextron III / IV or Synthetic ATF
 

Allison Transynd, in my race cars and daily drivers. None better!

Re: Dextron III / IV or Synthetic ATF
 

Curious about Allison Transynd. Allison recommends it for all of its transmissions and requires it on newer 3000 and 4000 series models. I have one of the older 3000's and can use either Dexron or Transynd. I have never had a problem with Dexron 3, if I change it once in a while.

I had planned to change to the synthetic, but a truck shop specializing in heavy duty Allisons told me not to waste my money. They said they don't use the synthetic because it is so expensive and they haven't seen any benefit.

What gives with all of these really expensive ATF's? The stuff required in the new Jaguar's is $20.00 or more a quart.

Thanks,

Loren

Re: Dextron III / IV or Synthetic ATF
 

Transynd is the same as TransMax , which is a Dexron synthetic made by Castrol. It is excellent .

Re: Dextron III / IV or Synthetic ATF
 

Normally, asking your transmission builder is best.

Re: Dextron III / IV or Synthetic ATF
 

Mobile 1 also has Allison approved Mobile Delvac Synthetic Trans fluid TES-295 #112810. Better blending stocks than Castrol.
I agree with Ed, your trans builder knows...

Re: Dextron III / IV or Synthetic ATF
 

At 20$/qt, how many qts go in an Allison 3000 series transmission?

StickBBF

Re: Dextron III / IV or Synthetic ATF
 

The Jaguar transmission fluid is a complete joke. I said $20.00 but I think it is much more than that from the dealer. The Jaguar transmission requires ten to 14 quarts.

The Allison 3000 requires about 28 quarts depending on the sump size. Allison says to change it every 75,000 miles.

The Allison 4000 requires about 40 some quarts depending on the sump size. Again every 75,000 miles.

If Dexron is used it is supposed to be changed every 25,000 miles. When I do that, it looks the same as the stuff I started with. Not dirty or anything.

Filters (two large ones) are very high quality and very expensive, never seem to get dirty.

The whole thing seems odd to me but rebuilding one of these things is VERY expensive, so I just bite the bullet. Just wish I knew more about transmission fluids.

Loren

Re: Dextron III / IV or Synthetic ATF
 

I have been reading a lot about them.
Cannot get a straight answer if they are all made by one source.
Then marketed under different names.
Then the confusing specification information between them to make them look different.

What I do see is that Synthetic behaves differently. Able to take more heat and offer better protection.
Synthetic different grip and lubrication properties over standard Dexron III/IV.
So much so that Synthetic lasts 3 times as long.

Wonder who has done a study on Dexron after 25000 mile change.
What do the properties look like after use?

There is Amzoil vs Standard, Amsoil vs Royal Purple, vs Redline

This was a fun youtube video.
https://www.youtube.com/watch?v=dntD3XmI8DM