In Reply to: fordson major transmission fluid posted by paul appleton on August 18, 2019 at 13:47:40:
The Fordson Major was a common sump machine just like the N's and the oil should be a mild EP gear oil - not conventional hydraulic oil. The Ford recommendation for those machines was the same as the 8N:
M-4864A - mild EP SAE 80 (winter)
M-4864B - mild EP SAE 90 (summer)
Either one of those grades would lift a full load in either season and a modern all season equivalent is Universal Tractor Transmission Fluid (UTTF). Ordinary hydraulic oil is not suitable for use in the transmission and final drive so it should never be used. But if an ordinary hydraulic oil was used it would have to be an extremely light grade to have any chance of causing this problem and that would only be at elevated operating temperature. It would still lift fine at cold startup. That of course presumes the pump and lift components are not worn to He!! and back.