I use John Deere Corn Head Grease in the steering box of my '35 fordor sedan (avatar). I had been using a mix of gear oil and STP, but it leaked out of the box very quickly. I didn't have time to rebuild the box and install new seals and gaskets prior to going on a cross country tour this past June, so I filled the box with JD CH grease in May. This cured the leaking problem completely and the car actually steers more easily.