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Looking for recommendations on what transmission fluid to run in my 51 200 with Ultramatic.

Thanks!

You want to use Type F ATF, Dexron & Mercon are too slippery for our Ultramatics and can cause the direct drive to slip. I use Pennzoil because it's available at NAPA and Walmart.

Type F is the foolproof choice but Dexron III should also work as long as the throttle pressure is adjusted properly and it will give a smoother clutch engagement.

Thanks guys!

Hi I been running B&M Trick Shift in my 51 300 for a number of years and all seems to be working well

Yup that works well however provides not really any noticeable benefit over Type F unless perhaps for very aggressive driving. As long as the clutches engage snappily then you're good.

I'm running Amsoil Super Shift synthetic in my '56 Clipper. It is for Type F applications and is designed to minimize slippage and promote positive clutch engagement.

This transmission was rebuilt and filled with Amsoil when I put the car back on the road so I can't compare it to this car's operation with another fluid. The Low to High shift is crisp and positive and the Driect Drive engagement is smooth and positive. The pressures measured on the external ports have all been within the appropriate value ranges across all tests with over 2000 data points. The fluid temperature has never been out of the acceptable range. Other '56 Clippers I have driven (these were using other fluids) have demonstrated harsh Direct Drive engagement and softer Low High shifts and similar Direct Drive engagement. Not enough miles have been driven to consider this as a long term test, so monitoring will continue.

What you noted depends also on the lining material. Packard used different materials for the bands vs. DDC but they are often relined to the same material now. Also the roughness of the drums were controlled from the factory but they are pretty much all worn smooth by now. So to test the fluid definitively, you would have to control these variables.

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This was noted in the initial condition description "This transmission was rebuilt and filled with Amsoil when I put the car back on the road so I can't compare it to this car's operation with another fluid." This is only a report of the objective and subjective observations I have made during the operation of one car operating with the transmission fluid I have chosen. I don't know what would make you think that this was meant to indicate a definitive test, that would require a transmission dyno a lot more initial conditions and thousands of times more data for each fluid you would want to test and compare.

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How have you measured "noticeable benefit"?