Q: Do I Need to oil my fretboard to keep it from drying out?
A: It depends. Most maple fingerboards are finished and therefore don't need to be oiled - just cleaned occasionally. Rosewood and ebony contain natural oils, but can benefit from occasional treatment - an unfinished maple fingerboard would definitely benefit from treatment.
People use all sorts of crazy things on their fingerboards - we've seen olive oil and motor oil suggested - but our recommendation is to use a product that's specifically designed for guitar/bass fingerboards. One rule: never use a product containing silicone on your guitar or bass. They never truly dry, and make repairs difficult later.