727 fluid- What to use?

Type F is about the last of the unmodified AFTs.
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)

Things have become far more complicated in recent years due to the computers for the automatics.
Dexron II or III is hard to find. Here's a repost from another list of my conclusions in 2008 as to
what commonly available fluid to put in a torqueflite 727 or 9xx.

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.

Of the modified ATFs, the options in order of preference:
1. Dexron VI. This is GM's current standard. By definition, Dex VI is
fully synthetic and has the lowest low temperature viscosity. That's
great for street and the first autocross run of the day. However, what
convinced me that this is probably the best current replacement (unless
Type F is wanted) was that several manufacturers specifically list
it as backward compatible to Dex III *and* Dex II.

2. Synthetics. Several manufacturers offer synthetics labled as
appropriate for Dex III applications. e.g. Mobile 1 Synthetic, Castrol
Syntec, Valvoline Synpower. But it seemed that if the manufacturer offered a Dex VI,
they stated Dex VI is the prefered replacement. (Valvoline, Mobile)

3a Dexron/Mercon. These are probably all fine - especially if the trans
has some leaks - since its generally cheaper than options 1 & 2. A lot of
people who post on the web and seem to be knowledgeable like to point out that
Dexron III and earlier 'no longer exist'. What they mean is that
GM is no longer licensing the early versions, therefore what is being sold may
or may not meet the former Dex III standards. My feeling is that may be
technically true, but the companies have other incentives to make sure
these products are what they say they are.

3b Dexron/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. Said to have better oxidation
resistance and improved seal life. Not all agree on the compatibility.

4. 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.

5. Mercon V. Seems to be the Ford version of Chrysler's ATF+. Also not
fully backward compatible.

6. Multi purpose: Probably the same as Dex/Merc, but better check the
manufacturers recommendations. Seems like too much of crapshoot for
people who care about how the autogear changer shifts.


These were my conclusions and obviously others may come to different conclusions. I've used Dex II and III, Type F, ATF+, Dex VI at one time or another in my own 727s. The only one that I was really unhappy with how it seemed to effect the shifting were the ATF+3/+4. I'm currently using Dex VI in the leak free trans and Dex/Merc in the Jeep with rear leak.
--
Matt
67 Barracuda nb 340 TF727
85 Grand? Wagoneer AMC 360 TF727 np229

type f/type f/type f!!!!!!!!

if type f is the way to go,what maufacturer?valvaline,castrol??or just any type f,also is for race or street use,or both

Allison TRANSYND fluid.

http://www.allisontransmission.com/service/transynd.jsp

there is better fluids out there but they are more expensive,theres absolutely nothing wrong with type f.the brand dont matter,its which ever you choose or prefer,ive ran it for years and no problems,especially if you run a stall converter,you would want to change the fluid fairly often anyways.some people claim that it breaks down and ruins the trans!maybe if you only change the fluid every 50,ooo,who does that?

Another vote for type F. Used it for years with no problems.

heres a ? I read on here that hydrolic fluid is even used and mixed with the tranz fluid

whats the opinion on that?

yea or nay..? can it be done safely?I just use the house brand dex/mec or F when I find it

does it matter on the mixing of the 2?

like said you cant get it all out,I just button mine back up with a manual VB..checked and no TC drain plug

Type F. Allways used it never had a problem. Local tranny guy here has been building high performence Mopar auto's for over 35 years. Allways recomended Type F. If it ain't broke don't fix it. I'll stick with what has allways worked for me. Type F

Not to specifically resurrect this thread, but . . .
Until Chrysler started recommending Dexron (the original) in 1967 or 1968, the prior spec was the "old" Type A, Suffix A atf that everybody used. Ford Type "F" and Dexron appeared in the same model year.

CAR LIFE magazine had an excellent article on the fluids' differences and similarities, all in the quest of "the smoothest shift". The article claimed that in the then-new THM400, GM put more capacity in the clutches so they could make them slip upon initial engagement, which is what Dexron did. Upon initial engagement until clutch "lockup", the rate of slippage was greater, then decreased to "no slip".

Ford went another way. They used less clutch capacity to temporarily over-load the clutch to cause initial slippage until clutch lockup. Their Type "F" fluid had a grabbier initial friction coefficient that made up for the intended slippage in the clutch pack. Therefore, with that initial grabbiness of the fluid characteristics, Type "F" became the defacto "higher performance" fluid at a time when only B&M TrickShift existed as the performance atf alternative. From initial apply to full lockup was of the same time period for both approaches.

In TorqueFlite 727s for 1966, Chrysler went toward the cherished "imperceptible" shift by replacing the "flat" steels (1965 and prior) in the clutch packs with "wavy" steels. That in itself, replacing the wavys with flats, makes for a quicker and firmer shift with normal atf, but unless you know what's what, many might never know it. This was with the old Type A Suffix A fluid.

In the Chrysler "Police Car" book, it mentions that in 1962, the CHP's new maintenance director desired to cut costs, so he bought 20W motor oil and used it in the TorqueFlites as well as in the engines. Only rule was that after an extended pursuit, the unit come in for an oil change of the trans. It was also noted that other brands of transmissions did not take kindly to the 20W motor oil in the automatic transmission.

So, by 1969, Ford was all Type "F" (the incognito "performance" atf), with Dexron in GM and Chrysler automatics. Dexron II addressed atf cooler corrosion issues (trans cooler in the radiator tank), as earlier mentioned Dex II-E was for electronic conrols, and Dex III soon replaced it in the 1980s decade. Dex II-E had a quicker shift than Dex II, by observation, but adding the GM Automatic Trans Conditioner additive (usually for higher mileage units) to Dex II resulted in a similarly faster shift. Dex III came in about the time of more sophisticated lock-up torque converters.

The newer Dex VI is a semi-syn fluid that GM claims is fully backward compatible to all GM transmissions to model year 1949. An Allpar.com article has some great information on the longer service life of the semi-syn OEM atfs. Plus that Chrysler desired backward compatibility, but full-syn had some issues with seals, so semi-syn was used.

In our then-new 1966 Chrysler, upon cold starts, the trans would have a little delay in things getting up to pressure. After the first transmission service, it became necessary to start it in "N", rather than "P", to not have any delays. Allegedly, the factory-fill fluid was a multi-vis fluid, but the replacement was not.

When the LH cars came out, the first atf spec was Dex III + a Chrysler additive. Using just Dex III would result in decreased clutch friction life. The trans controller would monitor for slippage and increase line pressure 100 times/second to combat it. With the friction characteristics of Dex IIi alone, it would hammer the friction material from the facings in the converter and clutch packs. That'w what I read and also confirmed that the fwd UltraDrives were notorious for "running fine" and then wouldn't move after they were parked. The module adjusted line pressure to combat slippage right until it was metal-to-metal in the clutches.

The Chrysler ATF+__ fluids came into being with the UltraDrive and later LH cars. As I recall ATF+3 was backward compatible for earlier automatics.

In later years, many changes to frictional characteristics of atf were made related to converter clutch issues. Some OEMs now modulate "lockup" levels (between 0 and 100%) depending upon operational environments.

GM is not licensing Dex III any more, as Ford is not licensing Type "F" any more, with "Dex/Merc" being the default replacement for Dex III.

Earlier on, it was claimed that if you used Dex in a Ford Type "F" spec transmission, the clutches would cook. Or if you used Type "F" in a GM trans, it would break, but only putting Dex in a Ford Type "F" trans might cause problems. Note that after a particular model year, Ford spec'd Dex for a few years before their "Mercon" fluid family came out. It's suspected that Mercon IV is very similar to Dex III but customized for Ford's desired converter lockup characteristics . . . plus some shops use Mercon IV where Dex III is spec'd

Many trans shops have their own likes and dislikes for trans fluid specs and what they will or will not work in. We've gone from a generic Type A Suffix A fluid spec to very specialized fluid specs over the past 50 years.

Back to the TorqueFlite without lock-up torque converters, historically you can use pretty much any common atf available. Some are a little ligter viscosity than others (faster shifts and better fluid flow), but common Dex III seemed to work just fine. In racing applications, a syn fluid (as Amsoil) works good, too.

The newer fluids have more additives and friction modifiers in them than any prior atf, with some being semi-syn or full syn. As GM claims Dex VI to be backward compatible to 1949, is a semi-syn, that migt be a good choice of "normal" atfs. There are plenty of higher-performance atfs, too. In any event, watch for color and smell changes in whatever atf you use and change it if those things change significantly.

CBODY67

Is that reality or simply an excuse to avoid having to have numerous different fluids on the parts shelf? Ditto for Mopar ATF+4.

CBody67, Nice addition to the thread. Thanks!

in racing applications more run tractor hydraulic fluid , haven't use it myself.