I have to confess to being a bit of a fan boy for Dave Reoame (Dave's World of Fun Stuff, youtube). He uses ordinary household surface cleaner to clean up fret board/finger boards. He then puts a few drops of linseed oil on and wipes it over the board. I have used lemon oil on my Rosewood and Ebony boards. All seem to work fine. Make sure there isn't any residue left from the oil though. Wipe it on and then off again.