I have a MIA Fender Jazz Bass American Deluxe Fretless, with a rosewood lined fingerboard. Unfortunately I like using Roundwound Steel strings (allergic to nickel) which I've been told are not good for rosewood as they wear the fingerboard. Does anyone know of a suitable oil that will harden the rosewood and provide some resistance to the wear created by the strings? I've heard that some oils will harden the wood but I'm not sure which... Thanks!