Dear Milton and mid-60s Buick tranny experts, . . . .
I know this sounds elementary but what transmission fluid should I be using in my stock 2 speed 65 GS automatic?
Of course the reasonable answer would be a transmission fluid that meets the specs for the transmission of the time. Somehow my trusty wagon never does seem to do the reasonable thing. At least for a time, she was running a TH200-4R that was custom built and the builder recommended of all things: Mercon V fluid. Yes Mercon is a Ford trademark and the TH200-4R is a GM product. Faced with that suggestion, Orinda Motors found a Mercon V and Dexron VI compatible fluid and that's what was in her TH200-4R.
Alas it didn't help, that tranny still leaked like a Sieve. Ultimately it got replaced with an Art Carr California Performance Transmission TH200-4R and I don't know what fluid they recommend. Still, perhaps it is worth pondering a later generation fluid at least if it is supposed to be backward compatible with the earlier fluids (and isn't too expensive.)
Cheers, Edouard
