hyd fluid
I would recommend doing some homework here. There are many many types of hydraulic fluid, and most of them are not designed for "wet clutch" type applications like transmission fluid is designed for. There are "heavy" trans fluids like Allisons and other heavy equipment trannys use that would be good choices, but I doubt any savings long term, especially if you puke one tranny from the wrong fluid... you can buy dexron in 5's at napa... or any chevron jobber store