i use caltex textrans tdh in the transmission and hydraulics of our machine. its a universal hydraulics, trans and diff oil for tractors of all kinds. originally designed for cane harvesters and hual-out equipment. it just so happens to be 75-80 gear oil and iso68 hydraulics oil. also suitable for tractors with wet brake systems. it has cat to-4 approval.

i would suggest a quality 20w50 or 20w60 mineral oil for the engine

Thanks for the info. I figure any lube I throw in it will be light years ahead of 1930s lube but more info is always better.

I got the blade moved to my place. Hopefully this winter I can get to work on this project. I still have plenty of other things pulling me in other directions.

One thing I noticed, it appears the air cleaner that was with the machine is not the correct one. It has a brass Donaldson tag on it, and I believe the air cleaners supplied with the R5 were a Caterpillar Vortox patent and marked as much. I will use this one unless a correct one happens to fall on my lap. I'm no purist, I like things to be period correct though, and this fill fit the bill.

our 50s model machine has a donaldson oil bath. according the parts book its factory. the pre cleaner had been changed to the plastic bowl like modern gear has.