For some reason this comes up as 'planet waves fretboard cleaner' when I bought D'addario hydrate.
This review is for D'addario hydrate;
Yes, it does 'roseacre' fretboards. They can be very dry (though recent Harley Bentons I've received have had well nicely oiled fretboards). Three coats of this helps a lot, and also with sharp fret ends - the dry fretboard expands. A lot of people are always saying what cheaper alternatives they use for oiling their fretboards but really, we're not using industrial quantities of this stuff - just get the stuff that's been designed purely for guitar fretboards. I haven't tried it on any vintage rosewood boards yet but I will.
I do read stuff about never using oil on a fretboard - in over 20 years playing, I've never once seen a fretboard damaged by having been oiled. Don't use pure lemon oil though - that can have a drying effect. Any of the good proprietary 'lemon oils' for fretboards will be fine though - there's not going to be that much lemon in them.
The D'addario hydrate has been recommended by people more in the know than me though. Fine for rosewood, ebony, 'roseacre' - don't bother with maple if the fretboard is lacquered - you can just use cleaner/polish on that.
