I have to partially disagree with you Denny Graham. The repair manual and owner's manual both call for steering lube not 80W motor oil. Even with a well sealed steering box, the 80W can leak out IMO and it definitely is not what would have been originally used.
I haven't tried cornhead grease, but since it is not available at any of the JD dealers around here, I did pick up a couple of tubes when I was in Western Idaho/Eastern Oregon last year. I have heard of some other alternatives, including the Penrite steering lube, which I believe is made for classic MGs. The cornhead grease does seem to be a good alternative as it is a semi-liquid, so it hopefully will maintain a layer of grease around the screw mechanism and balls in the steering box, and it is much cheaper than the Penrite stuff. Plain old lube grease is a big no-no. As mentioned, a cavity can form around the moving parts eliminating the lubricant between them.
