[KULTULZ]

Good overall description of period fluids -

The original trans fluid spec for almost everything in the USA prior to 1968 was "Type A, Suffix A" automatic trans fluid. Earlier versions didn't have the "Suffix A" designation.

Type F ATF was a Ford exclusive fluid from 1968 until they started having many different fluids in the 1990s. That was the same year that GM came out with their GM-spec "Dexron" fluid. Chrysler eased from Type A Suffix A into Dexron in '68, also, as the supplies and ready availability of Type A Suffix A fluid dwindled.

The difference in Type F and Dexron differed in their frictional characteristics of the "initial apply" of the frictional units in the trans. GM added clutch capacity to their trans so they could use a fluid with a less agressive (i.e., "smoooth") apply whereas Ford went the other way, with more agressive apply and less clutch capacity, so "intentional overload" would result in a slight amount of "slip" due to the lesser clutch torque capacity, friction material wise. CAR LIFE magazine had an article on this subject, back then, with graphics of the clutch/band apply actions of each transmission.

Type F fluid was a "hot rod trick" for GM transmissions, sometimes mimicing a shift kit installation with the "more positive" shifts. B&M Transmission products seemingly patterned their "TRICK SHIFT" fluid after the way the Ford Type F fluid behaved, but that's speculation based on the way a GM trans acted with Trick Shift in it.

In later years, manufacturers have found somewhat better ways to modulate shift harshness/firmness. Line pressure variations and electronic controls are some.

When my grandmother was driving the '58 Fairlane (292-2bbl, F-O-M), I distinctly recall how positive the initial engagement was going into the forward drive ranges or "R" from "P" or "N". That was when Type A fluid was still around. On that orientation, I think I'd use Dexron to lessen the initial shift shock for the drivetrain (u-joints and rear axle internals).

I'm somewhat surprised that NAPA showed the Type F rather than the later Mercon V fluid. In many cases, Dexron III and Mercon V are sold with the same branding, but I suspect the Mercon V fluid might have a better base fluid stock than Dexron did as I know a few transmission shops who converted to Mercon V rather than use Dexron III. In that older trans, I believe I'd NOT use the newer Dexron VI fluid . . . it's believed to be a blended-synthetic base stock and is more expensive. Seems that the Mercon-spec fluid had a better anti-shudder friction modifier for lockup torque converters, which would not be applicable here.

ONE distinction between the Ford ATF, whether Type F or Mercon V, is that they are also rated for power steering use. Dexron-family ATF is not, as GM has their own specific power steering fluid. Although Ford has allegedly ceased licensing the Type F oil, it's still available from Motorcraft.

In the USA, Type A fluid is still around, but not in the usual places. It used to be prevalent in the convenience stores and food stores, of all places, plus some older auto supplies who had clientel who had older vehicles which needed it.

The NAPA recommendation of Type F might be due to the recommendation of Valvoline for Type F fluid in "Ford products prior to 1980". Of course, by the time 1980 came around, people had forgotten about Type A spec fluid and it was well known that Ford automatic took Type F fluid (at least from 1968+), until later transmissions needed specific fluids. I suspect that if you look around, you'll find some Type A fluid somewhere.

From my own experiences, I'd NOT put Dexron in any power steering unit . . . the rubber seals and o-rings are not compatible with that fluid, causing seeps and weeps . . . all of which stopped when I bled the system and put normal (Chrysler in this case) PS fluid in the system.

In the world of GM, though, they recommend the most current Dexron fluid (Dex VI) to be backward compatible all the way to 1948 in GM automatics. ONLY Type A fluids existed back then. My concern about using Dex VI in earlier transmissions is that in some cases, seal materials might not have the longevity they need to have with a fluid that has some or more synthetic in it than the orig fluid did. Hence, Dexron/Mercon multi-make fluid.

This might be a somewhat complicated answer, but there are several ways to look at this situation.

Regards,
NTX5467

QUOTED SOURCE - https://forums.aaca.org/topic/197099-ford-o-matic/

TYPE F is still readily available. TYPE A(s) are now used mainly for dirt bike trans usage

MERCON V is a partial synthetic and supersedes all previous FORD MERCON types. If you have a problem using a synthetic, DEXRON is still available in the old blend (GM). FORD only uses MERCON V. If the car is a late model, check OWNERS MANUAL or MOTORCRAFT LUBE CHART for proper fluid type.

FORD used(s) DEXRON and/or TYPE F PS FLUID according to period application. Again, OWNERS MANUAL

FORD and GM went their separate ways in 1961 as each modified their trans for different shifting firmness. TYPE F was not introduced until 1967 for the 1968 model run.