Finally put my trans back together in the 59 fury. Completely rebuilt with a kit from fatsco. I used some dexron III to presoak everything and as assembly lube. Guys at fastco said all the seals and clutches are made with todays materials so any dyno or synthetic is my choice. Would the latest atf+4 work. Latest dexron? Or stick with the tried and true dexron III?

Thanks, Brian

Type F. Just a little less friction modifiers, allows for a slighter faster clutch hookup.

When you say friction modifiers, do these make the fluid grip more or slippery?

slippery

Considering how much those cast iron TFs weigh I use lighter fluid.

Sorry, just couldn't resist.

Friction modifiers can make the fluid either more slippery or more aggressive...in the case of type F, it's more aggressive.

Make sure you read the section(s) in the service manual on Torque converter and bell housing alignment to the transmission, Lest you may waste the trans in short order. Ask me how I know ??

To answer your question, Dexron 1- 2 -3 works fine

That's because Type F has no FM. A HFM (highly friction modified) fluid like ATF+4, on the other hand, allows much more slippage of friction materials. Dex is somewhere in between.

Friction modifiers can either increase or decrease the coefficient of friction a fluid has, depends on what the formulator wants.

Again, John, see my post above. Type F is "grippy" (less slippage of friction materials) because it has no FM. Dex has a moderate amount, and ATF+4 has a high amount (that's why it's called a HFM ATF). I know of no ATF that uses increased amounts of FM to make it "less slippery". If you can provide any credible evidence of one, I'd be very interested in seeing it.