What fluid for a 4-speed trans?

mcodecuda said

This is an interesting discussion. It might not happen until Carlisle but I’ll ask Herb Mccandles what he suggests the next time that I see him. I’m originally from Syracuse New York which was home to New Process Gear where all of the 833 4-speeds were built. I’d would have asked my NPG buddies the question but most of them have passed away.

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The factory recemmended different weight of fluids depending on how you drive and where you live. If my 66 was driven in the winter months like it was when it was newer, I would probably run ATF. 80-90 would be too stiff at -20°. None of us drive our old cars in extreme temps so a thicker 80-90 would be fine. I was having some hard shifting issues with mine. I would imagine it still had the original 80-90 in it and the car had sat for years. I used the Pennzoil Synchromesh and it made it work pretty good. I recommend that.