the 1/2 and 2/3 shifts on that trans,, are a hydraulic shift {no electronics involved} other than a govonor signal ,,,,depending on the
vintage of trans,,,possible a hydraulic govonor signal,,,,,synthetic additives are ok lub guard or the like ,,,,,"conditioners" on the other-hand,,,, attack rubber components,,,,,,makes them like gummy worms,,,,,not good!!!!!!! dextron 5 or any synthetic ATF works too!!!