For all versions of the Ultramatic, the factory originally called for
Type A automatic transmission fluid (ATF). An improved version of fluid was later announced (see
SC Vol. 29, No. 8) for the Twin Ultramatic,
AQ-ATF - also known as
Type A, Suffix A. However, neither of those formulations is available today.
In the beginning, there was no fluid specification for any automatic transmission other than
Type A, but as mechanical technologies evolved, so did fluids. By the 1960s, Ford had developed
Type F to replace
Type A for its transmissions. GM continued to specify
AQ-ATF, until the late 1960s, when it introduced
Dexron. However,
Type A,
AQ-ATF, and the original
Dexron formulation could no longer be produced when whale oil, used as a friction modifier, was eliminated in the 1970s, due to a moratorium on whale hunting. During the 1980s, Ford migrated to
Mercon, which was essentially the same as
Dexron II. The evolution of ATF types gets progressively more confusing as time goes by, as a succession of synthetics blends began to emerge in the late 1990s.
Getting back to Ultramatics, my father, who went on to a GM store after working as a mechanic in a Packard dealership, had once told me to use
Dexron in place of
Type A. Recent online explorations affirm that
Dexron is backwardly-compatible to
AQ-ATF and
Type A.
However, after a complete drain and refill (including the converter) with
Dexron II in my '56 Patrician, I noticed a moan from the Direct Drive clutch (when engaged) under light throttle. I worried that a full tear down and clutch replacement was needed, but before I ever got to that point, similar complaints from others who had tried
Dexron revealed that refilling with
Type F often provided relief.
In the absence of other hydraulic/mechanical issues, ongoing discussion, here, continues to favor the use of
Type F in units that have original equipment or factory-approved replacement clutches and bands.
Supplier data describes
Type F as a high static friction fluid that allows the shifting clutches to lock up or engage quickly. Put simply,
Type F is
"more sticky" than
Type A, while
Dexron is
"more slippery". Friction modifiers used in
Dexron offer a smoother shift, but that suggests increased clutch slippage, which might lead to faster wear of the linings.
On the other hand, one has to wonder if the
Dexron formulation might be more appropriate for those units which have been rebuilt using modern, GM-type, friction materials.
Kanter Auto seems to indicate that it is NOT required with their kits:
https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=2812&forum=4&post_id=29244#forumpost29244 We've not heard from other suppliers (yet).
Although I haven't checked on the availability of
Type F, locally, I found web pages featuring the product from major suppliers, like
Mobil,
Pennzoil and
Castrol.
Type F also seems to come up online discussions in agricultural circles. However, I've since read that
Type FA will replace
Type F.
Meanwhile, some owners - following a tip from member
Turbopackman - have reported improved performance with their Ultramatic by using
B&M Trick Shift fluid, which I've heard is essentially
Type F with dye and a friction-modifying additive.
In conclusion, both
Dexron and
Type F appear to be acceptable alternatives for the Ultramatic; the choice depends on how your transmission is built and performs.
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