1946-1949 Early Hydra-Matic Transmission Fluid

[Cadillac Jack 82]

Personally Dex/Merc III work fine with the gals.  Had a hard shift in the 55 but added some Lucas and boom...gone.

[Michael Brittan CLC #2750]

The ATF transfusion took place as planned.  The transmission took 12.5 quarts of the Dex/Merc, just like the shop manual says it should.  I have only managed to put a few miles on the car since.  My initial impression is that there is a small improvement in the 2-3 shift, but more extensive driving is required when time and weather permit. I'll report again when I have racked up some more miles.

[Michael Brittan CLC #2750]

Latest update:  After a few more miles on the road, my initial impressions following the ATF transfusion remain - i.e. a small improvement.  Tim's observation that Lucas treatment fixed the hard shift on his '55 is interesting, and may be worth trying, though possibly counterintuitive.  I would expect the Lucas additive to increase the viscosity (as per TJ Hopland's post) and therefore maybe exacerbate a hard shift.  On the other hand, maybe a slightly more viscous fluid might slow down the mechanical transition involved in the 2-3 shift and therefore be of benefit.  Any words of wisdom before I try this?