For what it's worth, I read on the P15-D24 forum that "Corn Head Grease", available from John Deere dealers is a good choice for steering boxes. I've purchased some of that grease, but have not added any yet. Supposedly, it will perform well, even if the steering box seal drips regular lube. My 1948 Plymouth has a bit of a leak at the steering box,, and I'm planning to give it a try.