I understand that Dexron transmission fluid is not to be used in Chrysler front-wheel drive transmissions, and that the correct fluid to use is ATF+4. I¹ve also heard that wear and damage can result from using the wrong fluid.
My ¹98 Town & Country transmission was recently overhauled by a local transmission shop. About 200 miles later, the trans started having trouble shifting and was slipping badly. Rather than take it back to the same shop, I took it to the local Chrysler dealer. They took it apart and showed me the disassembled transmission. It appeared that the original shop did rebuild it correctly, replacing the clutches and gears. But the clutches were badly burnt and had to be replaced again. It was then that I found out that the original shop used a Dexron/Mercon fluid instead of ATF+4.
My question is: Could using the wrong fluid have caused the clutches to burn out so quickly? I don¹t see any other explanation. Wouldn¹t this be considered negligence or incompetence on the part of the people who used the wrong fluid?
Also: What is it about Dexron that causes damage to Chrysler transmissions?
[To reply by email, replace the last letter of the alphabet in my email address with the letter "p"]
Absolutely the Dexron could be responsible for the damaged clutches. The earlier Chrysler TSB's that OK'd changing over older vehicles that came with earlier types of ATF to ATF+4 excluded certain vehicles from the approved changeover list. The reason for the exclusion of those vehicles specifically cited potential for damage to the clutches.
NOW - a later TSB superceded that one and added in those previously excluded vehicles (which I believe were certain years of the minivans). I'm not a transmission expert, but the fact that there was caution and delay in approving the preciously excluded vehicles tells you that the fluid properties are critical to preventing clutch wear/damage. But I don't know how you prove it.
The transmission service industry is convinced that Dexron? with an additive is equivalent to ATF+4, and uses the circular argument of their own trade journals to "prove" it.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
I very much doubt it. The trans shops that substitute the cheaper Dexron use a "shift improver" fluid (Lubegard is a popular one) that changes the sliperiness of Dexron to make it match ATF +4, I'm sure that yours did too. But even if they didn't, 200 miles is way too short.
A number of years ago I bought a 1995 T&C that had 20,000 miles on a rebuilt transmission. Being the suspicious type as soon as I got it I looked up the specs and read about the transmission fluid issue. I then called the rebuilder and asked them what fluid they used - Dexron, of course. Needless to say I changed the fluid out. The van is still running fine.
I think that the simple answer is that the shop that did the rebuild simply didn't put the transmission back together again properly.
I think that is immaterial. After only 200 miles you have a warranty claim and I would pursue it. If you paid for the rebuild with a credit card I would call the card company and get the charge disputed. With a signed statement from the Chrysler dealership that the rebuild was done wrong, you have a pretty open and shut case from the credit card company's point of view. If the shop that did the rebuild is stupid enough to come after you, you can sue them for fraud pretty easily.
I would avoid getting involved in telling the shop that did the rebuild what the problem was. Your not a trans expert, your word is meaningless. What you need to do is call the rebuild shop and explain what happened and tell them you want a refund. If you don't have the credit card dispute mechanism you may have to settle for a negotiated refund if they did in fact replace gears or other hard parts - since those parts were not damaged. If they want to call the dealership and get the story from the dealership as to what was done wrong, that is their business.
transmissions?
There's been a number of theories but I have never seen a scientific analysis even by Chrysler so I take the theories with a grain of salt. What is strange is it would be rediculously easy to setup a test rack, and put a fresh trans in it, instrument the hell out of it, then fill it with Dexron, then run it until it died. Then we would have definitive proof as to what it was.
The theory I've read that seems the most reasonable is that the trans computer is programmed for a certain "slipperyness" of the fluid, and Dexron is too far off spec, as a result the computer thinks the clutches haven't engaged when in fact they have, so it attempts to reengage the clutches multiple times, this wears them out quicker. But this smells like a theory generated by someone sitting in a chair and guessing, it does not sound like an actual description of an instrumented trans in a test rack with Dexron in it.
Personally, my gut feeling is that the longevity of these transmissions when run with Dexron + shift modifier fluid is much, much, much closer to that of ATF +4 than Chrysler is comfortable with. I think if the failure was spectacular and rapid, Chrysler would have by now created a video or some such to show the difference and the Internet would abound with stories of people putting the wrong fluid in and blowing their transmissions. Instead, Chrysler seems content to allow the transmission repair people to dream up speculations as to what the real issue is.
Naturally, this is not an endorsement of Dexron in these transmissions. But the plain fact is that if it was well proven that using Dexron would shorten the life of these transmissions by only, say 15%, then a great many people who I'd classify as "bottom feeders" would use Dexron to save a few bucks.
To do it right, multiple units would have to be simultaneously tested along with identical units of the same lot filled with the correct fluid
- ATF+4 as a control. The cost of the experiment just went up. But no-one has the incentive to make the investment since only the consumer is getting screwed regardless of the truth of the matter.
Funny - you never hear of Consumer's Union doing this kind of telling testing, when it seems that it fits exactly in their charter. Why is that? Must not be any money in it for them either.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
Because the average consumer has no understanding of what real product testing is all about, and so does not demand better than the schlocky testing that Consumers Union and also Consumer Reports does?
It's possible. Dexron would most likely only directly damage the torque convertor clutch, but when the TC clutch lets go it sends fluff all through the rest of the transmission and that could have blocked the filter and caused low pressure, which could have then burned out the rest of the clutches.
But that's just a hypothesis, it could have been any number of things.
It has the wrong differential between its static and dynamic coefficient of friction. In other words, a clutch lubricated with Dexron III will slip easily, but then grab when it stops slipping. ATF +4 has a much smoother transition between sliding and sticking because the static (stuck) coefficient of friction is much closer to the dynamic (slipping) coefficient of friction. The torque convertor clutch in Chrysler electronic automatics (and now virtually all other manufacturers, but Chrysler was the first to use this system in 1989) is designed to be used in a partial-lock mode, where its engaged but deliberately slipping. This is done in 2nd, 3rd, and 4th gears (now 5th and 6th too on newer transmissions) to improve fuel efficiency by reducing fluid coupling the losses in the convertor at the high end of each gear. But when the clutch is being deliberately slipped like that, Dexron III fluid will cause it to "grab" over and over causing a noticeable shudder. That will also begin to break the friction material off the TC clutch, and then it contaminates everything else or plugs the filter. When the filter plugs, fluid pressure drops and the servos can't keep the other clutches firmly enough engaged, so they slip and burn out.
I've seen that kind of clutch burn out if the shop failed to soak the new clutch in AFT before they were installed. If the clutches were put in the transmission dry, they won't last more that a few hundred miles. The use of Dexron will make it shift horribly but I doubt that the use of Dexron would "burn" the clutchs that fast. Either way, the shop is at fault. Not much of a transmission shop if they don't know to use ATF+4.
I bet if you surveyed the local tranny shops where you are, better than
90% would tell you they would use Dexron with an additive vs. ATF+4. The aftermarket service world is eat up with bad information.
I called four shops in my area (two of which were highly recommended by everybody and their brother) and asked them what fluid they would use in my 2nd gen LH car, and all four said they'd use Dexron with additive. I changed the fluid myself.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
The last time I had an electronic Chrysler transmission rebuilt, I bought and carried in 3 gallons of ATF +4 and said "humor me- use this." And they did.
This seems to be fairly common. I had the transmission in my 1993 Voyager rebuilt last August. When I went to pick it up, I ask the shop owner what they filled the transmission with. He said that he used dexron with Lube Guard. When I expressed my concerns, he pulled the empty bottle out of the garbage, and showed me where it says that it meets Chrysler's requirements. The shop has been in business for many years, and does warranty work for several dealers.
Anyway, the transmission is working fine so far. The Automatic Transmissions Rebuilder's Association warranty runs out in August. At that time, I will probably replace the fuild myself and use ATF+4, just for my own peace of mind. Chrysler labeled ATF+4 can be bought at Walmart for about $4.50 per quart.
I can understand why shops do not want to stock every kind of fluid that is required by each manufacturer. At the same time, the transmission fluid issue has been covered extensively in this NG. The general opinon has been to use the recommend fluid, which is now ATF
+4.
On another note, in my van's early days, I used to take it to the local Chrysler / Plymouth dealer for transmission service. Each time, they would replace the fluid with ATF+3 (that's what was available at the time) along with a "conditioner." When asked them about the conditioner, they said that it was to ensure that new fluid would mix okay with the older fluid. When I mentioned that Chrysler does not recommend any additives, he stood by his position.
I still don't know what the additive was, or who made it. I tend it was a way for them to make a few extra dollars.
Chrysler's requirements for which fluid? There are several Chrysler fluids. You can't simultaneously meet the requirements for all of them. The aftermarket manufacturers know this but are very dishonest in their labeling, and the shop owners are willing to play along them for their benefit, not the vehicle owners, *knowing* that the label is misleading. They are dishonestly inpolying that if it's printed on a label, it must be true in every possible context. The shop would be hard pressed to find in print anywhere in their literature that it specifically met the requirements of ATF+4 in a way that could stand up to a court challenge.
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
I believe that the Chrysler specification for ATF+4 is MS 9602, while the spec for ATF+3 is 7176. I don't think it is possible to meet both specifications simultaneously, although ATF+4 should now be ok for transmissions previously built for ATF+3, per Chrysler service bulletins. (Those MS numbers are from memory, so I may be off). I believe MS stands for Mopar Specification or similar.
That assumes that a bottle labeled as meeting spec xyz actually does meet it.
local Chrysler parts dept tells me you can run ATF+4 in an older ATF+3 trans but once you put it in, you cant go back to +3
don't know how legit that is but I don't want to risk it myself, and since ATF+4 is now available at Wally world, I'll stick with it since I started using it.
Nonsense. Although there's an enormous amount of effort by Chrysler to mystify this fluid, the frictional coefficient between ATF+3 and ATF+4 is the same. The only difference is that ATF+4 is synthetic oil, ATF+3 isn't. ATF+4 lasts longer in the transmission before breaking down, because of this.
Which is a VERY good thing. ATF +3 was HORRIBLE fluid when it came to oxidation rate and other degenerative processes. Both Dexron III and Mercon V were vastly superior in longevity, but of course simply wouldn't work right in a Chrysler automatic because they had the wrong friction properties. ATF +4 fixed the degenerative properties of ATF +3 wile maintaining the right frictional properties.
I don't believe this because after ATF +4 was introduced Chrysler did not vastly increase the servicing interval for use of ATF +4 vs ATF +3 in these transmissions. I think your being misled.
ATF+3 was manufactured by other people than Chrysler. However, with ATF+4 Chrysler has control of the additive package, and no matter where ATF+4 is sold, and by whom, Chrysler gets a cut of it.
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