Originally posted by Dr Wanker Ebony is MORE prone to shrinking and cracking then rosewood which is a naturally oilier wood. A little light mineral oil every year or so is plenty.
I've heard exactly the opposite: ebony is the densest-grained fingerboard wood there is and should never need any oil at all, except perhaps to clean it if it's really grungy, otherwise leave ebony alone. And rosewood has a coarser grain than ebony, which makes it more sensitive to changes in the relative humidity, so I'd say it needs oiling occasionally.