There are two schools of thought here. One agrees with the dealer. The other says grease it to properly lube and clear out contaminants. Once greased, keep at it, the grease attracts abrasives and they need to be cleaned out.

I use grease. No problems but I do it pretty regular. I'm more concerned with moisture causing rust up here in the rain forest of NW Oregon. If I were in a dry climate, I wouldn't worry about it.