Thoughts on ATF+4 in GM 4T60-E

[440Magnum]

Originally Posted By: keith
Will ATF+4 work in place of Dex3? Who can answer that? I don't believe there is a definitive answer.


No, there IS a definitive answer for that (at least for Chrysler transmissions that formerly required Dex III). And it is YES. Nothing in +4 adversely affects any component of, say, a 1980 A-998 or a 1969 A-727, or a 1992 A-518. ATF+4 friction modifiers are for TC clutch characteristics, and nothing had to be changed in the other clutches or in the band materials to be compatible with it. Chrysler even flatly says that its OK for the Aisin-Warner AW4 in Cherokees. But given that Dex VI should also work in all of those I named and is a more degradation-resistant fluid, that's probably what I'll use the next time my two A727s and my AW4 need a change (actually the AW4 already does need a change...)

Given all that, its quite likely that GM transmissions that called for DexIII will also tolerate ATF+4... but why on earth would GM (or anyone?) advertise that fact or test for it? There's no reason to do so.

I do recall that there is an exception or three somewhere on Chrysler's list of transmissions originally calling for DexIII or ATF+3 that are compatible with ATF+4, but its a real oddball. Maybe the Benz gearbox in the Crossfire, or one of the 1980s Mitsubishi re-badges? I forget, it was one that will never matter to me.

 

[KCJeep]

Interesting discussion. My own experience converting an older GM tranny to Dex6 from DexIII was not good, troubles started shortly thereafter. I will never know for sure if it was the change but I'd not do it again.

 

[440Magnum]

After pretty much reading this whole thread, I think people have kinda forgotten what went so horribly wrong in the early days of ATF+3: It was a very specific failure mode in Chrysler electronic transmissions (namely, the A-604 later re-named 41TE). It was not because the lack of ATF+3/4 friction modifiers hurt the primary drive clutches. It was because DexIII allowed the torque converter lockup clutch to shudder, eventually making it shed its friction material, which then FUBAR'ed the valve body, servos, and other components. Drive clutch failures and valve body failures were secondary to the TCC failing.

 

[pbm]

Originally Posted By: keith

The universal will most likely have more or less friction modifiers than the original fluid, more for some and less for some. Seems to work ok for most people.

I have only two data points. Switched ATF+3 for Amsoil Universal in a Dodge Caravan. Transmission slipped badly. Drained it and put in ATF+4. Worked great for the next 150K miles until we sold the van. Switched SP-III for Amsoil Universal in a Hyundai Elantra. Transmission slipped more than before. Drained it and put in ATF+4. Works great, now at about 100K miles on the ATF+4.

Will ATF+4 work in place of Dex3? Who can answer that? I don't believe there is a definitive answer.


I have 5 quarts of Genuine Chrysler ATF+4 that I purchased at WM for my-b-I-l's Neon which has been sold. WM no longer carries this stuff so I can't return it.
I had never even thought of using it in my 4T65E but I have thought of using oit in my 2008 Elantra since Hyundai once spec'd ATF+3.....To answer the OP's question...I wouldn't use it (personally) in a GM..

I am currently running Maxlife in my Elantra w/o a problem.
Am I right in thinking that I could use the ATF+4 in the Elantra w/o an issue?

PS: Knowledgeable BITOGer Undummy (who hasn't posted in a while) was very high on ATF+4 in many applications because it is an excellent fluid.

Keith: What year Elantra did you use ATF+4 in?

 

[MolaKule]

Quote:
I know that trans slips the torque conveter clutch quite a lot each lockup by design so that the operator does not feel it, and that is one of my dislikes on that tranny. That slip is unnecessary and not sure how the ATF+4 would do there...slip more?


ATF+4 is slightly more friction modified than are the Dexrons and would cause an increase in clutch slipping.

 

[440Magnum]

Originally Posted By: MolaKule
Quote:
I know that trans slips the torque conveter clutch quite a lot each lockup by design so that the operator does not feel it, and that is one of my dislikes on that tranny. That slip is unnecessary and not sure how the ATF+4 would do there...slip more?


ATF+4 is slightly more friction modified than are the Dexrons and would cause an increase in clutch slipping.


My understanding is that the FMs in +3/+4 suppress the static (non- sliding) coefficient of friction so that it is nearly equal to the sliding coefficient of friction. This prevents the clutch from "catching" as it reaches full engagement, and thus prevents TC clutch shudder. Think fingernails on a blackboard- the screech comes because your fingernail slides more easily once its moving, so it repeatedly catches then slides, catches then slides. A friction modifier would prevent that.

The FMs used in +3/+4 should NOT make a healthy clutch pack more likely to slip or fail to engage fully, but it might make the final engagement feel a little less definite- the driver can't as easily tell when it reaches full lock. IF it causes actual slippage leading to burnout, then the clutch pack was effectively dead already.

Old-school racers will remember that Type F transmission fluid is even less friction modified than Dexron III. It used to be used by racers because they felt it made the transmission shift harder. What it probably did is just make the shifts feel firmer more than actually speed the engagement in a meaningful way.

 

[MolaKule]

The original fluids were built with specific wet clutch dynamic friction coefficients.

Here is a another explanation:

ATF Friction coeffieincts

What we're saying is if you draw a graph of the coefficient of friction on the vertical scale, Mu or(u) verses the RPM of relative rotating surfaces, (v), you will see a curve with different slopes for Type F and the other fluids which determines how much torque is transferred at various rpms.

A full synthetic Type F is best for racing because of the solid and quick transfer of torque when the clutches engage.

Ford Type F is still used in racing modified transmissions such as PowerGlides and TurboHydromatics (TH350 and TH400), etc.

I still formulate this fluid for regional racers.

Another reason for the "jolt" in racing transmissions is that the modifications result in high fluid pressures to the clutch pack and bands.

An additional consideration is that any increased slippage of the clutch plates and TCLU assembly in a transmission results in increased heat at those surfaces which raises fluid temperatures.

 

[pbm]

So what's the consensus on using ATF+4 in a Hyundai Elantra that specs SPIII?
(Not trying to hijack the thread but I think this might be a more appropriate application than a GM).

 

[il_signore97]

Originally Posted By: keith


Universal ATF manufacturers have satisfied themselves that the fluid won't immediately blow up your transmission. Maybe it won't shift as well, shift better, wear quicker, wear slower, but whatever, they are happy to take your money and have calculated that it will more than cover any warranty claims. The universal will most likely have more or less friction modifiers than the original fluid, more for some and less for some. Seems to work ok for most people.

I have only two data points. Switched ATF+3 for Amsoil Universal in a Dodge Caravan. Transmission slipped badly. Drained it and put in ATF+4. Worked great for the next 150K miles until we sold the van. Switched SP-III for Amsoil Universal in a Hyundai Elantra. Transmission slipped more than before. Drained it and put in ATF+4. Works great, now at about 100K miles on the ATF+4.

Will ATF+4 work in place of Dex3? Who can answer that? I don't believe there is a definitive answer.



It's unfortunate that you didn't have the same luck that I had using a high quality universal synthetic ATF (Amsoil in my case, but I've read many good things about Redline as well). My vehicle history speaks for itself. Many different specs, no failures, nothing even close to worse shifting or performance. No adverse changes to the material collection on the pan magnets, etc. I couldn't see any downside in my vehicles with my use. It even kept my Intrepid tranny running for over 300k km before selling. Those were notorious for failing in the warranty period, let alone that far after.

 

[Whitewolf]

Originally Posted By: Wampahoofus
Before the raging firestorm ensues, I know +4 is not the spec fluid for this trans and won't yield any major benefits besides enhanced longevity and more consistent performance. Now, carrying on:

Does anyone have prior experience using Mopar ATF+4 in a GM trans that originally spec'd Dex-III? I have a bunch of it on hand and would like to take advantage of its more-consistent performance and longer service life compared to Dex-III. I would be using it in a 2000 model 4T60-E with 180k miles on it.

It has had the fluid and filter changed at least once around 100k, so it shouldn't be on the verge of complete death. I'm unsure if it's been done more than that.

After studying Chrysler's SAE paper 982674 my gut reaction is that it would be fine. Both fluids are nearly identical in terms of cold and hot viscosity, and perform very similarly in service (until the Dex begins to degrade). Backing that feeling up, Chrysler superseded many of their Dexron-II factory-filled units' fluid with the ATF+ series. In the early days of the A-604 they also claimed ATF+ and Dex-III were interchangable (though we all know how that turned out in the Chrysler transmissions).

"If you want a good synthetic fluid, why not use Dex-VI? GM said it's ok for your application." - I would, but I have a ton of +4 lying around.

Thoughts? Feelings? Objections? All much appreciated

Don't. I have the friction curves and you do not want to go there.

 

[Wampahoofus]

Whitewolf - would you be willing to share some of your data on the different friction coefficients? Nothing proves an oddball idea wrong quite as well as cold, hard facts :-D Annoyingly, my sources give a pretty good account of this for +3 and +4, but nothing on Dexron.

The SAE paper I quoted initially appears to support what 440Magnum said about the static/dynamic friction coefficients being very similar. When testing +3 and +4's friction coefficients against the sliding speed of a sample of torque converter clutch material, the paper quotes:

"The observation of negative slope (increasing coefficient of friction as the sliding speed decreases) has been shown to correlate with transmission shudder."

The way they illustrated it this effect was judged unacceptable only at very low speeds, 0.1 m/s and below.

Additionally, +4 was considered superior because it's static/dynamic friction coefficient ratio was closer to 1 than was +3's (0.91 vs. 0.88).

 

[oilmutt]

What is the make and model of the GM ride?

 

[Wilhelm_D]

Originally Posted By: pbm
So what's the consensus on using ATF+4 in a Hyundai Elantra that specs SPIII?

It's been done. Many Chrysler dealerships do it for their Mitsubishi-based models with transmissions that call for SP-II and SP-III.

 

[Whitewolf]

Originally Posted By: Wampahoofus
Whitewolf - would you be willing to share some of your data on the different friction coefficients? Nothing proves an oddball idea wrong quite as well as cold, hard facts :-D Annoyingly, my sources give a pretty good account of this for +3 and +4, but nothing on Dexron.

The SAE paper I quoted initially appears to support what 440Magnum said about the static/dynamic friction coefficients being very similar. When testing +3 and +4's friction coefficients against the sliding speed of a sample of torque converter clutch material, the paper quotes:

"The observation of negative slope (increasing coefficient of friction as the sliding speed decreases) has been shown to correlate with transmission shudder."

The way they illustrated it this effect was judged unacceptable only at very low speeds, 0.1 m/s and below.

Additionally, +4 was considered superior because it's static/dynamic friction coefficient ratio was closer to 1 than was +3's (0.91 vs. 0.88).

I'll try to see what I am able to provide but using BW 4329 material in an SAE #2 machine using the standard GM 200 hour test the Chrysler fluid fails on midpoint torque at about 30 hours! Published information SAE 2007-01-3987.

 

[Boss302fan]

I would use Maxlife ATF in your tranny...

 

[keith]

Originally Posted By: pbm
Keith: What year Elantra did you use ATF+4 in?


It's an '07. Just checked it last week and the ATF+4 is as bright and fresh as the day I put it in, after approx. 6 years and 100K miles. At 30K miles, the SP-III was in bad shape. SP-III is junk.

 

[440Magnum]

Originally Posted By: MolaKule

Another reason for the "jolt" in racing transmissions is that the modifications result in high fluid pressures to the clutch pack and bands.


And (IMO) this is the desirable way to firm shifts for racing in an old-style fully hydraulic transmission. The problem I have with throwing Type F into a transmission solely for the purpose of firming the shifts is that it causes the clutch packs to grab at a point where they are under lower clamping force on them from the servo than they would achieve by using a more friction modified fluid and increasing the clamping forces by raising the fluid pressure, and also the rate of fluid delivery to the clutch packs so that the clamping force rises faster. Clamping force is your friend in a multi-plate clutch because it helps prevent the clutch material from failing in shear mode. Using a "grabby" fluid with slow stock servo apply rates and low pressures can (again IMO and experience) increase the shear stress in the clutch material so that it fails faster. Modify the transmission, not the fluid.

IME, the best-built street/strip automatics still drive reasonably tamely on the street, yet shift very hard under heavy throttle. You can have it all if you address every aspect of the shifting process- servo pressure apply rates, servo holding pressures, and line pressure VS throttle position (Chrysler) or line pressure VS manifold pressure (Ford and GM), clutch plate count, clutch material, and the intended fluid to be used.

 

[MolaKule]

Quote:
IME, the best-built street/strip automatics still drive reasonably tamely on the street, yet shift very hard under heavy throttle. You can have it all if you address every aspect of the shifting process- servo pressure apply rates, servo holding pressures, and line pressure VS throttle position (Chrysler) or line pressure VS manifold pressure (Ford and GM), clutch plate count, clutch material, and the intended fluid to be used.


Very Good point. You have to take the whole system into account.

That's why our racers use special geometry fluid pumps and blueprinted valve boring/programming to achieve just that.

Our experience is that a low vis 4.5 cSt fluid with a Type F additive package with a higher level of AW gives us the performance we need.