It was recommended (somewhere) and I have used teflon trailer hitch grease - very slippery and long lasting.
To Richard: I just dropped the rudder on my 35 and did it previously on my Catalina 30, it's pretty straightforward, the first problem being: do you have enough vertical space to lower it so that the rudder shaft clears the hull. For the Catalina, I dug a hole. For the O'Day, I'm parked on asphalt so digging wasn't an option - the boatyard just jacked up the stern of the boat (only needed about 4 inches in my case). Before dropping it, you need to access the steering quadrant and remove it from the rudder shaft. On my boat, you have to remove the liner in the port rear lazarette and then you have a good view of the quadrant. Put a jack under the rudder, disconnect the steering cables from the quadrant, remove the bolts holding the quadrant halves together, push out the bolt that goes through the quadrant and the rudder shaft and then remove the quadrant halves (may need to pry a bit). At this point, your rudder is ready to drop. In my case, someone had replaced the quadrant/shaft bolt with a stainless steel pin that was frozen in place - it took a lot of pressure to remove it, big mistake. If yours has a bolt, it shouldn't be too bad to remove. Make sure you use some corrosion inhibitor (Lanacote, Tef-gel) when you put it back together so it comes apart easily the next time. The photo below shows an O'Day 35 quadrant: the yellow circle marks one of the bolts that secures the steering cables, the red circles mark the bolts that keep the quadrant halves together and the green circles mark the center bolt that goes through the quadrant and the rudder shaft.
