High specificity of oils, coolannts poor design per se

In my opinion, making assertions with absolutely no logical arguments to back them up is poor design, in and of itself.

Ted

If you are refering to the A604 / 41TE tranmission that require a specific fluid, then as much as it pains me, I have to disagree.

When I was growing up, there was Dexron for GM and Ford Type F. You knew not to put Type F into a GM and visa versa.

The fact that too many trans shops want to cheapen out because their owners think they know more about transmission design than the engineers who designed the tramsmission - just so they can save $10 on a $2000 rebuild is NOT the fault of Chrysler!

Now, having said that, I DO think that the A604 in its initial releases over the first 10 or so years was a bad design! It had not been properly tested and proven, and DC foisted a huge "design of experiements" on the car users at the expense of those users - for which they should be made to pay IMHO.

Even the refined designs of the A604/41TE are more stable and reliable, they still are too light for the applications. As a result, they still fail "prematurely" when compared with older more robust tranmissions.

People expect better. They are not getting it. This alone proves the design is inappropriate for the application and is therefore "Bad". But this has nothing to do with the fluid that is used, and everything to do with either the failure of DC to anticipate cutomers needs, or the outright arrogance of DC to know better and screw its customer anyways.

:)

That's a lot of good points you make. But I think in this case, Chrysler, as it was known before being bought up by the German Daimler, ought to have spelled out in big, bold letter the dangers of not using ATF +3. Even ATF +4 might be a problem because it was synthetic and a bit more "slippery" than the dinosaur ATF +3.

This is way too much of a burden to place on those who know little about transmissions and Cottman. For example, I have read here that these cars in the beginning, early 1990's or 1989, did not have ATF +3 specified on the dipstick but Dexron. Is that true?

In testing done during development of ATF+4, Chrysler noted the following viscosity loss from shearing for the following ATFs (20 hour KRL Shear Test):

Dexron III - 40% loss Mercon V - 19% loss Type 7176D - 32% loss Type 7176E - 14% loss Type 9602 - 10% loss

You can see what a significant impact the new viscosity improver had on ATF+3 when you compare the 7176D and 7176E numbers. From the standpoint of viscosity loss alone you can see why Dexron III should not be used in transmissions that require ATF+3 or ATF+4. In terms of other basic performance parameters, ATF+3 (7176E) comes the closest to ATF+4, with Ford's Mercon V a close second. [Which doesn't mean that Mercon is acceptable.]

The goal in developing ATF+4 was to create a fluid that would match the performance characteristics of the current fluid (Type 7176D), but would retain those characteristics for at least 100,000 miles. The paper specifically notes that the anti-shudder properties of ATF+3 are usually degraded enough by 30,000 miles to cause noticeable shudder.

Contrary to popular myth, one of the stated goals of Type 9602/ATF+4 fluids was that it would have the same frictional characteristics as ATF+3. The paper explicitly states that this was because new clutch materials would not be introduced for this fluid and it had to be backwards compatible with ATF+3. Graphs in the paper show that the friction coefficient of fresh ATF+3 and ATF+4 is essentially identical, but as the fluid ages ATF+4 retains the "as new" coefficient while ATF+3 degrades.

-----------end of quote----------------

So now I see my use of ATF +3 is limited but still. I need to have the fluid changed or expect the infamous shudder which did occur at 30,000 miles, on schedule. The 4th gear in this electronically controlled transmission became extremely demanding for a minivan which is a family car not a racing vehicle with very critical specifications.

All in all, that 4th gear and electronics was not worth the aggravation and expense.

Damn straight. Insist that all engines work on 30-weight non-detergent oil, and all transmissions on good old Type A ATF.

That's forward thinking alright... :-p

ATF+4 is now available at all the auto parts store and according to several service bulletin replaces the ATF+3 used in most DC vehicles. My 04 TJ even uses AFT+4 in the powering steering system.

Coasty

That is forward thinking. Your trivializing, hmmm almost corrected that to you're trivializing, maybe this is a gerund?, gerund who, anyway, his opinion and mischaracterizing it makes me think - you're not a compassionate conservative by any chance :)

If a vehicle requires extremely specific fluids, then this info needs to be promulgated expeditiously. And some explanations would help. Eventually this information did come out but about six years after the fact. It took that long to finish the alpha testing. Now we are in the beta testing period.

At this rate, we will be up to revision 1.0 soon. Onward and forward over the trannies littering the salvage grave yards.

Damn skippy, indeed.

Nondetergent oils DO work fine in all engines IF they are changed often enough. Unfortunately, often enough is not possible. Detergents used in oils contain stuff like calcium, barium and magnesium which form deposits that glow in combustion chambers and cause preignition. That is why diesel engines can and do use oils like Shell Rimula that are NOT okay for spark ignition service. Aircooled spark ignition engines should use nondetergent oils if no filter is used, or an ashless dispersant if one is.

Still, designing engines with moderate oil consumption, eliminating hot spots, and keeping operating oil temperatures in reason along with minimizing extreme pressure points and providing good crankcase ventilation means engines work with more modest oil specifications.

That's good for everyone. And ithe same idea applies to automatic transmissions. Design around good old Dexron and youi are good to go.

Its easy to trivialize a silly statement that isn't deserving of "compassion." There are valid engineering reasons for specific fluids these days. Reasons that aren't just for the convenience of engineers. Things like reducing emissions, increasing efficiency, and allowing the engine (or other system) to operate in regimes that drastically improve performance, but would not be possible with "generic" fluids.

You mean like maybe in the OWNER'S MANUAL?!?!?

I assume you do know, don't you, that the latest API ratings *are* in some ways "more modest" than older ones? They demand smaller percentages of anti-scuff additives that were highly important in engines with flat tappet cams and gear-driven oil pumps, but completely superfluous with roller cams and crankshaft-concentric oil pumps. That's one reason that Mobil 1 Extended Performance is one API rating back from the standard Mobil 1... and also a reason I use Mobil 1 EP in my older engines but use regular Mobil 1 in the newest ones.

Good to go.... slowly and inefficiently with poor shift quality and more frequent fluid change requirements than if you design around ATF+4.

Yep. 87 caravan with a 3l V6 has "USE DEXON III" on its stick

You just blew your own argument apart with that statement. Which Mercon would that be? mercon III? Thats a newer fluid than some, wasn't the original fluid anyway. So, someone edcided that the fluid needed improving to match improving slushboxes. for what reason have you decided to stop development at that particular fluid?