[AT] transmission oil/fluids

[John Paur]

To those of you that understand oils and lubricants:  Is the modern transmission/hydraulic fluid (eg. Hy-Trans and similar products) suitable for use in the older transmissions.  I'm thinking of the Farmalls, John Deeres etc form the 1930's and 40's.  How about the modern GL-5 transmission oils?  I've heard that additives in some of these are detrimental to some of the bushings and seals.  Any truth to that?   Thanks for any feedback.  John