I disagree. The last time I took a transmission into a shop to be rebuilt, the shop charged me $950 to do absolutely NOTHING. The trans still had problems after being "rebuilt" so I opened it up myself and found worn clutches, even though I GAVE the shop a rebuild kit with new clutches when I dropped the vehicle off. The shop did discount that price to $750 because one of their employees stole the stereo out of the vehicle and damaged the dash doing it. Gee whiz, I really won't trust anything that shyster has to say about anything, much less transmission fluid.

Run Dexron VI for the same reason you don't run bias ply tires - technology moves on and the original factory recommendation may no longer be the best thing to use.

But as others have said, its your car, run what you want.

Cool story bro, but what does the fact that you got screwed by some cheap hack have to do with the subject at hand? Pretty sure no fluid will save a bad rebuild.

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Official Cookie and Mater Tormentor.

It attacks the credibility of your claim to always listen to the transmission "rebuilder" because (a) they must be honest and (b) must know what they are talking about because they "do it for a living." If you have found a rebuilder who you trust, great, listen to them. I haven't found such a person, so I am not going to listen to them. What I do trust are independent scientists who test and certify various chemicals and automotive fluids todetermine that those fluids meet predetermined standards. Dexron fluids are backwards compatible. Dexron VI supercedes Dexron III. Ergo, I will use Dexron VI.

There are many fine, competent, honest transmission rebuilders, but transmission shops, for whatever reasons, have a high prevalence of dishonesty and incompetence. The chain/franchise outfits like SCAAMCO drive that figure up, but there are a lot of bad independent apples, too.

There are questions that are best answered by the person who does [whatever] for a living.
There are other questions that aren't, even though it might feel logical to do so. Here's an(other) example: no matter how many police officers and EMTs issue how many opinions on whether the airbag or the seatbelt or whatever other feature saved the life of the crash victim, the appropriate response is to smile, nod, and appreciate the difficult job they do while realising that job does not qualify them to be issuing those kinds of opinions. They're not lying, they're stating what they think they understand of what they think they see, but their expertise isn't the relevant kind for that question.

Many other questions, answers, and situations are like that.

(Psst: why does the NASCAR racer have STP stickers all over his car? Is it because he uses STP in his race car, his personal car, his lawnmower and his electric toothbrush, and he's a racecar driver for a living so he oughtta know? Or is it because STP pays him for those stickers to be there?)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I would assume that Bill had his trans built by someone he likes/trusts and not the lowest bidder down at Joe's Diner and Auto Repair.

I stated that newer fluids are probably better than Type F. I also stated that you can't really measure any useable difference in a hobby/daily driver car.

If spending extra money makes you feel better, by all means do it. Personally, I follow the advice of the guy who built it and will be eating the warranty if it breaks.

The trans that I had done for my Valiant has a trans brake and high stall converter. It will beat the fluid harder in 4 passes than most street cars in a year. I was going to go to synthetic fluid in it. My builder said no. It gets Type F.

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Official Cookie and Mater Tormentor.

Me, too! I rebuild all my own transmissions!

For whoever might care: in the United States, the Magnuson-Moss Warranty Act of 1975 prohibits a warrantor from tying warranty coverage to the use of a specific brand of repair part (air filter, oil filter...) or maintenance supply (engine oil, transmission fluid) unless the warrantor provides that part or supply free of charge. The warrantee (that's the buyer/owner of the item covered by the warrantor's warranty) may use any brand of part or supply of their choosing, as long as it meets the applicable specifications. Dexron is the well and widely documented spec for an A904 or A727 transmission, so you get to use whatever brand of it you choose to use and, by federal law, doing so cannot void your warranty.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Hey Dennis, your tranny builder wants you to run Type F fluid because he knows you want that tranny to shift hard, dig on the clutches and cut good times at the strip. He also knows that you will bring the tranny back in to him every year or two for a look inside.
Type F does not have the lubricty of modern Dextron, so it will shift harder, you and I both know B&M Hydrofluid is type F repackaged, intended for those hard shifting drag racing auto trannys.

I am believing that the original poster, WAJR wants street / track performance, but is not planning on pulling the tranny ever, just for a look inside,, hence he should use modern Dextron and give up that .005 edge at the track you may be getting with the harder grabbing Type F.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

While it is true that oil technology has advanced, (I did not ever dispute that) 904 technology is still the same as it was 40 years ago. Oils have improved because new car technology improved, and Type F will not cut it in any newer trans because it was not designed for the parameters of new equipment. I sure would not put it in the 8 speed in my truck, but it works fine in 727's and 904's because they were designed to use what was available then.

My contention is that using the latest, greatest oil will not show any measurable gains. A 904 is reliable as an anvil. Dexron, Mercon, Type F, whatever will make it operate fine and live a long life. I know people who use JD 20 hydraulic oil and even 30w motor oil in them. I sure wouldn't, but it works for them. 904 isn't a Ferrari transmission ferchrissakes.

If the guy who built it says use "X", use "X". No need to reinvent the wheel just because you can.

Just for argument sake, when Keith tore down my original trans he did for my Duster it had 50,000 street miles and 1500 or so passes on it. There was not so much as a nicked thrust washer in it. I attribute that way more to it being built properly in the first place than to what bottle the fluid came out of.

By now Bill has probably gone to the store and bought whatever he wanted to anyway.

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Official Cookie and Mater Tormentor.

That’s very interesting , thanks.

As an example if someone purchased a rebuilt engine from a reputable supplier with full warranty and was silly enough to cheap out and buy the cheapest EBay special filter they could find from off shore that met the specs and it collapsed and caused failure of the engine due oil starvation I would assume the supplier of the engine would be at liberty to prove that part was defective and send them on their way to take the issue up with the filter manufacturer? At best they would end up with a new cheap filter and left with burned up engine? Or is the engine rebuilder still required to honour his warranty?

If they followed the rebuilders preferences and fitted his recommended brand filter and it still failed would it give them any more leverage for engine warranty? Legally I’d imagine they would be left in the same situation either way, but I’m interested to hear, but I’d still feel I’d have a little more face to face leverage with a reputable builder if I followed his preferences, just perhaps he would follow it up through his suppliers and get some action, maybe. At least I’d feel I would have improved my chances for a warranty from a reputable shop.

As for fluids, well, there’s plenty of people running happy and long living TF trans with type F for performance duties , plenty of C4s as well for that matter. One way of looking at it is less slippage during shifts actually reduces wear and the frictions. That’s their opinion and it seems to not create any issue I’ve seen. One respected Mopar builder has zero issue recomending this fluid to his performance customers and has a fine reputation for building long lasting trans. Is it the recomended fluid? Nope, but are race builds warranted anyways? Likely not so it’s a moot point.
For a driver TF? Sure Dexron of whatever Spec is available. That’s what I use, it’s cheap,plentiful and it works for my drivers,it’s not a race car. Simple, no fuss no issues why waste the money on anything more exotic. That being said I believe the latest Dex is of a slightly lower viscosity so a check of pressures and or shift and converter behaviour would be of interest but likely of no major issue. Now, If I had a performance 3 speed TF build I would not hesitate from running type F from what I’ve seen and been told from people whose opinion I respect.

As for recomended fluids meeting warranty requirements then from the ones I’ve seen,most of the multi Spec synthetics meet Dexron, ATF +4 and type M Spec as well as a myriad of others, so no issue with warranty since they meet the required Spec . So run what makes you feel good and gives you peace of mind, your trans won’t really care, it’s all waaaay above the original Spec.

Hummmm.

Boy oh boy, a can of worms this thread turned into, LOL

Zilla: As Dan previously said: "ding, ding, ding."

I spent the weekend nailing down 3/4" x 3 1/2" natural red oak flooring in #1 son's master bedroom, the last room to be finished in his four bed room two story colonial ending a nearly year long project. Working around a house full of furniture, nasty wall to wall carpet, moving lower kitchen cabinets, repairing some sections of sub floor, replacing a back door, a wall removal project, four kids & dog added to the excitement level during the 2400 square foot job. I never once turned on my PC during the weekend, too beat-out to haul my fright to basement office and back up to my dent in the couch. Note to self; too old for floor jobs.

Friday I was out shopping with Mrs wjajr, when the old frugal Yankee/ cheap bastard gene kicked in. I picked up two gallons of transmission fluid for use in vehicles previously serviceable by Dexron III or Mercon which fits the bill for the old 904. I'll probably be draining it out within 24-30k miles for a band adjustment and filter change.

A side from a badly worn tail shaft bushing, and seals, one of the bands was mostly cooked, I suspect a result of previous owner not having throttle position cable or linkage attached. Shortly after getting this heap back on the road in 2008, a kick-down cable was installed.

Thanks for all the input, lively discussion, and testimonials; all very entertaining.

Bill

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

...which rigourously-measured data demonstrate doesn't actually happen to any significant degree. This is practically a myth.
Nope.
Yup, that's exactly what it is—not more.
The Torqueflite is a very well-engineered transmission that will withstand a great deal of abuse, including the use of inferior transmission fluid.
Your opinion might change if you were to look at the actual data rather than relying on poorly-informed opinions.
The marketers of those fluids claim their one fluid meets all those specs, yes, but claims aren't quite the same thing as reality. And there's at least one additive maker claiming their miracle additive "converts" Dexron into other fluid types, which isn't actually possible. But there's money to be made, so.

Relevant refs: This, , this*, this, this, this, and some others.


* This is where most of the "Dex-6 is better than ATF+4" data comes from. Because of SAE rules, the fluids compared could not be called out by name in the published papers. They are as follows:
A: Dexron-VI
B: Mopar ATF+4
C: ZF factory fill
D: Honda Z1
E: Toyota WS
F: Ford Mercon 5
G: Allison

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Yeah, but what do all those white-coated scientists know, anyway? I bet most of them never have even been to a race track or even tried running type F fluid in a 727!

Just like every other time certain subjects come up: engine oil viscosity, oil filter brand, rubber vs. polyurethane bushings, whether or not your chewing gum loses its flavour on the bedpost overnight…

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The marketers of those fluids claim their one fluid meets all those specs, yes, but claims aren't quite the same thing as reality. And there's at least one additive maker claiming their miracle additive "converts" Dexron into other fluid types, which isn't actually possible. But there's money to be made, so.


So...I go into a parts store and buy a reputable brand fluid (not additive) that “Claims” to meet or exceed these specs as clearly stated on the label. I should not believe it ? “Reality”,not exactly in what terms your referring to there ....I take it you mean like people who actually use the product? Experience? Like guys with type F or something? how do I know that Dex is really that if it’s just what on the label...it could be the evil type F in disguise