ATf+4 vs DEXRON VI in an OD Chrysler Transmission

[wrcsixeight]

On another forum I frequent, A poster who posts and knowledge I have learned to respect, recently said it is better to use Dex VI in any application that calls for ATF+4 as it is superior in every way and backwards compatible.

Call me Dubious.

What say you?

 

[earlyre]

atf+4 always. it's readily available, and fairly cheap if you have a walmart nearby. as long as it is a licensed atf+4(which ST is), it's pretty much the same. very restrictive formulations for the licensing.

 

[The_Eric]

It may be okay for use in the old transmissions that called for Dexron, but there's no way I'd use it in one calling for ATF+4! WAY different additives.

 

[901Memphis]

ATF+4 is highly friction modified, much more so than DexronVI so it could certainly present issues using DexronVI in the wrong application.

The older transmissions and even some of the late models RWD transmissions seem to be more tolerant of the incorrect fluid but if you take a late model FWD chrysler and drain all the ATF+4 and replace with DexronVI you will have immediate noticeable chatter and shifting issuds. issues.

 

[wrcsixeight]

Thanks. The transmission would likely be an A500 or A518 RWD, later 80s or early 90's possibly through 2003.

I have an A-500 and i know that the Universal bulk fluid used by Aamco when they rebuilt it caused torque converter clutch chatter on the engaging of OD/lockup at 47 to 60MPH after being in there for 10K miles, and was immediately rectified when I had a Dodge dealer exchange it with atf+3( in 2003)

I have done multiple pan drops since with ATF+4, and it has never shuddered again, and have no intentions of ever using any Dexron. I was just surprised to see this recommendation from somebody Whom i know in the past was ATF+4 only, now saying DexVI was superior in every way and should be used instead

 

[Kuato]

IIRC there were a few years where Chrysler transmissions could use other fluids, but once the +3 and +4 came out that period ended - and there were many transmissions ruined because the owners didn't use the ATF+4.

 

[901Memphis]

You got shudder with the wrong fluid there's your answer the guy is wrong.

 

[wrcsixeight]

Well my shuddering was when it was filled with whatever fluid + plus extra special magical secret sauce additive, that Aamco used which would yield them the most profit back in 2001.

Likely a very different fluid than Dex VI or ATF+4

Anybody got specs as to viscosity and other characteristic differences between these two ATF's?

 

[901Memphis]

They usually use lubegard Platinum mixed with a mineral DexronIII or Dex/Merc type fluid. It's made for this purpose but it's a terrible idea if you ask me to try to convert a fluid.

Since they usually use a mineral based fluid it would shear pretty quickly from around 7.5 cSt KV100 to under 5 cSt in short order

ATF+4 usually starts out at 7.5 cSt just like DexronIII used to although ATF+4 is much more shear stable than the mineral based fluid. DexronVI usually starts out around 5.8 KV100 and is very shear stable also.

 

[JC1]

Originally Posted By: The_Eric
It may be okay for use in the old transmissions that called for Dexron, but there's no way I'd use it in one calling for ATF+4! WAY different additives.


+1.

 

[doitmyself]

Supporting 901 Memphis' excellent info:

This has probably been answered before. How can the universal fluids like Maxlife, BG, Amsoil, etc., cover so many fluids with such different viscosity and I imagine friction characteristics??

 

[VNTS]

Use an ATF+4, if you want something better try Redline C+, full syn just for mopar transmissions.

 

[Oldmoparguy1]

Originally Posted By: wrcsixeight
On another forum I frequent, A poster who posts and knowledge I have learned to respect, recently said it is better to use Dex VI in any application that calls for ATF+4 as it is superior in every way and backwards compatible.

Call me Dubious.

What say you?

All the old Chrysler AT's used something called ATF, pretty much like what was used in the GM's of the period. ATF morphed into Dextron, then Dextron II. I have a Dodge car in storage that has "use dextron II " imprinted on the dipstick. When they started putting lockup TC's in transmissions they had to come up with a different fluid. Originally ATF+, then ATF+2 , then +3, now +4.

Do not use Dextron VI in any trans that calls for ATF+4.

 

[Ramblejam]

However, if no one points out "silly mistakes", you end up with a guy that's spent 12 years on an oil forum, and accumulated over 5,000 posts who talks about Dextron.

 

[tomcat27]

I would always use ATF+4. my understanding is that the differentiator is whether it is hydraulic or electronically controlled. that the electronically controlled must have atf+4.

 

[Johnny2Bad]

ATF+4 or buy a new transmission sometime in the next 40,000 miles. You decide.