Not too often though?
It's not good to oil too often, only when the fretboard looks/feels a bit dry.
Also, maybe every 6 months or year, you can take a razor blade and lightly scrape in between the frets to get the finger grime off the fretboard. Then a little steel wool, to polish up the frets. Finish off with some lemon oil, and your fretboard will look brand spankin new.
I will oil the finger board about once every 6-8 months or so, once it starts looking dry as you said.
Hmmmm....
That may not sound right.
-K
giggidy giggidy goo