Depending on how often you run, you can probably get away with greasing the shaft about once every few months, unless you run in salt water, which will mean a wash off after every run and a re-oiling as well.

As regaeding the greasing of the shaft, I use a medical seringe minus needle filled with axle grease, pump grease into the shaft about 10mm of travel on the seringe is enough then slide the shaft up the stern tube.

If you fill the stern tube completely with grease THEN put the shaft up the boat, you get a mess inside the boat, and sometimes a motor caked in grease! that happenned to me when I regreased my najade for the first time.