Max-Props should be greased once a year. This can be done in or out of the water. If the boat is in the water year round you should have a diver in the water at least once a year check anodes; they can grease the propeller at that time. Or, if the boat is hauled every year, it is easy to grease it while it is out of the water. We recommend Lubriplate 130 AA grease.
Check out the Barnacle Dissolver to clean your propeller. It's a safe easy way to clean the barnacles off your propeller.