Oil for rosewood fretboard, yeah...I use Gibson Fretboard Conditioner on mine.
As for the neck itself I'm afraid oils and such do not provide sufficient protection for years and years to come. I like to seal the wood properly to keep the neck straight and even. That means laquer. Been testing various methods...last one I did, I sprayed it with spray varnish, and then rubbed immediately all over with 0000 steel wool. The wood sucked in the varnish well, and I repeated the process six or so times, it only took an hour between to dry it seems. It turned out very silky, feels like wood but there must be plenty of varnish there anyway...so that seems like a good method for wood-feeling satin finish now. Will have to keep examining how it behaves onward.
Usually, and almost on all my guitars, I have a vintage style hard lacquer sprayed and properly buffed to full shine. Both vintage yellowish or clear, depending on guitar. I have no factory finished guitars any more, they're all custom and usually finalized (laquered/buffed) by a pro luthier, even though I've done the base work on most. Takes nearly a month to dry well, though. But that'll last forever and look great and certainly seal the wood well - after all that's the way all 50's guitars were done and they're still fine and have lasted well.
Dee
"When life's a biatch, be a horny dog"
Amps: Marshall JVM 410H w/ Plexi Cap mod, Choke Mod & Negative Feedback Removal mod, 4x12", Behringer GMX110, Amplitube 3/StealthPedal
Half a dozen custom built/bastardized guitars all with EMG's, mostly 85's, Ibanez Artwood acoustic & Yamaha SGR bass, Epiphone Prophecy SG, Vox Wah, Pitchblack tuner plus assorted pedals, rack gear etc. for home studio use.