transmission fluid

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trudysduster

trudysduster

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What is the best transmission fluid to run in the 727 and 904 tranny when changed. The ATF+4 or the Dextron/Mercon and can you mix them. I have a 69 that has only 70,000 miles on it and I had to replace the pan gasket and pan because of a leak. I believe the last time I did this I used ATF+4 but cant remember. Thanks,Bill
 
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I use non-synthetic Dexron III or IV can't remember which.
I was told by Cope Racing to not use synthetic in the old Torqueflite. Perhaps with modern seals , synthetic is o.k.

Whatever you use, don't buy the cheapest.
 
You can' to too wrong with Dex/Merc.
Whatever you buy, check the label to see if it is specifically a replacement for Dex III.
 
ProTrans that build my transmissions for Street and race cars
recommends Type F. I have been using it for 40 or 50 years and it
seems to shift a bit firmer and the clutch discs usually look great when
I rebuild it.
I use the $5.00 fluid at Walmart and it works great = Never seen any
difference between brands.
 
iScamp said:
I use non-synthetic Dexron III or IV can't remember which.
I was told by Cope Racing to not use synthetic in the old Torqueflite. Perhaps with modern seals , synthetic is o.k.

Whatever you use, don't buy the cheapest.
Click to expand...
I used full synthetic royal purple and it ran cooler with my higher stall converter. I've had this fluid for 10 plus years now no issues. No leaks either. Knock on wood!
 
They all work. Dex 3/mercon, type f, +4
Run whatever you can get for the cheapest. Personally I run type f and advise people I build transmissions for to run type f, street or strip doesn’t matter. However, recently a guy I built a transmission for couldn’t get type f and asked if dexron was ok, I told him yes.

Marco Abruzzi had a fluid designed recently that is basically a mixture of type f and dex3. It’s $40 a gallon but I can guarantee you it’s good stuff.

ATI sells type f synthetic and recommends type f for ALL transmissions.

Lucas makes a racing semi synthetic type f that I have used this year. Haven’t seen any difference between it and the rural king type f I used previously or any other type f for that matter.

I freshened a glide for a friend before this season. He runs ATI super f and doesn’t change the fluid for HUNDREDS of runs. His trans looked great inside.
 
You can run 30w motor oil in it and it'd never know the difference. And that's the truth.
 
There is really no reason to use type F with modern friction materials. The majority of the type F transmissions I've torn down or freshened have had the bushings burned out of them. I don't recommend it to people. At the minimum I recommend Dex III napa part number 75-200, which is made by Valvoline. That fluid will still cook fairly easy in high horsepower applications, however.

Really depends on what one is trying to accomplish, and their maintenance program (or lack thereof). Some folks that race certain classes try to keep heat in, others that might make more power and/or buy more than one tech card will try to keep the temp down--which is where some of the high dollar synthetic racing fluids come in.
 
Duster346 said:
There is really no reason to use type F with modern friction materials. The majority of the type F transmissions I've torn down or freshened have had the bushings burned out of them. I don't recommend it to people. At the minimum I recommend Dex III napa part number 75-200, which is made by Valvoline. That fluid will still cook fairly easy in high horsepower applications, however.

Really depends on what one is trying to accomplish, and their maintenance program (or lack thereof). Some folks that race certain classes try to keep heat in, others that might make more power and/or buy more than one tech card will try to keep the temp down--which is where some of the high dollar synthetic racing fluids come in.
Click to expand...
I tend to agree, even though I have run Type F in the past. I think it all boils down to what you are doing. For most street cars and cruisers and even the occasional strip run car, Dexron III is fine. But more than that and you probably should be looking at something more modern. I cannot agree with the keeping heat in.....although like you say, some do it. I think the fluid should be as cool as possible.
 
Walk the sportsman pits at a national or divisional event and you'll see cords coming out from under the cars on some stock and super stock cars--Heating pans on the oil and transmissions pans.

Typically, cars will be more consistent with heat in the drivetrain.
 
Duster346 said:
Walk the sportsman pits at a national or divisional event and you'll see cords coming out from under the cars on some stock and super stock cars--Heating pans on the oil and transmissions pans.

Typically, cars will be more consistent with heat in the drivetrain.
Click to expand...
I've seen it. I'm hard headed. I still wouldn't do it. lol I believe it though. That's gettin too serious for me. If I ever get back on the track again and I hope to, it will be for one reason only. For fun.
 
@trudysduster seemed to be looking for a basic answer. Of the ATF available today, Chrysler spec'd Dex II , superceded by III, for the Torqueflites. so look for an ATF bottle/website labeled replaces III.

Technical differences between F and the others is friction modifiers.
All of the Dex/Merc and related ATFs are friction modified. The modified ATF's change the way the clutches and bands grab and hold. All things being equal, the clutches and bands will grab quicker and harder with an unmodified ATF than a modified ATF. (They also may effect the release)

Type F. It's in a category of its own.
The only unmodified ATF with a dynamic coefficient that increases as clutches and bands lock up - resulting in firmer shifts.
If that's what you need, great. Drawback is that the fluid doesn't hold up as long. Result is often what @Duster346 has observed.

Dexron and Mercon - a chronology.
Gleanings from the web which appear to be more substantial than wild rumors, but you've been warned.
Dexron II 1973 - 1987
Dexron IIe was for electronic controls & had extra cleaning agents.
Mercon 1992- Contained less wax than Dexron
Dexron III c.1993 - Similar to Mercon. Lower low temperature viscosity than earlier versions of Dexron. Said to have better oxidation resistance and improved seal life.

ATF+3, ATF+4. Similar to Dexron but formulated specifically for
Chrysler transmission control modules. All of the manufacturer spec
sheets I found on-line seemed to agree - NOT recommended for DEX 3
applications.

Dexron VI. This was GM's latest standard (c 2008). By definition, Dex VI is fully synthetic and has the lowest low temperature viscosity. That
could be great for street and the first autocross run of the day. Several manufacturers specifically list it as backward compatible to Dex III and Dex II. I've used one of them. It's expensive, and if you have lingering doubts about using it, that cynicism seems reasonable to me.

I've used Dex II and III, Type F, ATF+, Dex VI at one time or another in my own 727 and 904s. The only one that I was really unhappy with how it seemed to effect the shifting was a ATF+3/+4.

edit: The current wikipedia page on Dexron seems very thorough. DEXRON - Wikipedia
and according to the following thread, is maintained by a Weber State prof John Kelly.
 
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Mattax said:
@trudysduster seemed to be looking for a basic answer. Of the ATF available today, Chrysler spec'd Dex II , superceded by III, for the Torqueflites. so look for an ATF bottle/website labeled replaces III.

Technical differences between F and the others is friction modifiers.
All of the Dex/Merc and related ATFs are friction modified. The modified ATF's change the way the clutches and bands grab and hold. All things being equal, the clutches and bands will grab quicker and harder with an unmodified ATF than a modified ATF. (They also may effect the release)

Type F. It's in a category of its own.
The only unmodified ATF with a dynamic coefficient that increases as clutches and bands lock up - resulting in firmer shifts.
If that's what you need, great. Drawback is that the fluid doesn't hold up as long. Result is often what @Duster346 has observed.

Dexron and Mercon - a chronology.
Gleanings from the web which appear to be more substantial than wild rumors, but you've been warned.
Dexron II 1973 - 1987
Dexron IIe was for electronic controls & had extra cleaning agents.
Mercon 1992- Contained less wax than Dexron
Dexron III c.1993 - Similar to Mercon. Lower low temperature viscosity than earlier versions of Dexron. Said to have better oxidation resistance and improved seal life.

ATF+3, ATF+4. Similar to Dexron but formulated specifically for
Chrysler transmission control modules. All of the manufacturer spec
sheets I found on-line seemed to agree - NOT recommended for DEX 3
applications.

Dexron VI. This was GM's latest standard (c 2008). By definition, Dex VI is fully synthetic and has the lowest low temperature viscosity. That
could be great for street and the first autocross run of the day. Several manufacturers specifically list it as backward compatible to Dex III and Dex II. I've used one of them. It's expensive, and if you have lingering doubts about using it, that cynicism seems reasonable to me.

I've used Dex II and III, Type F, ATF+, Dex VI at one time or another in my own 727 and 904s. The only one that I was really unhappy with how it seemed to effect the shifting was a ATF+3/+4.

edit: The current wikipedia page on Dexron seems very thorough. DEXRON - Wikipedia
and according to the following thread, is maintained by a Weber State prof John Kelly.
[/URL]
Click to expand...
I have a slant 6 with a 904 . After reading all these replies, I dont know a damn bit more than I did when I posted this thread. but thanks to all of you for your time in posting.
 
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