I've just oiled the ebony fretboard on my Elan using Lemon oil as recommended.  An idle question: why lemon oil?  What is it about lemon oil that makes it special?  Are there alternatives?
 
With greetings from NZ
Grant

If you do a search you'll find an answer.  It was something about lemon oil containing exactly some of the naturally occurring compounds in ebony that are lost when the wood dries out.  I think we discussed some alternative oils, but I don't remember anything else being declared worth using.

And there is the added bonus of a nice fragrance for a few days!

No alternatives..lemon oil is the choice for all guitar fretboards which are darkwood.
Put plenty on and let it soak in..you will be surprised how much does considering your bass goes into smoky venues and lives at home in air conditioned and heated homes.
I knew one person who used aerosol furniture polish until I put him right!!! I guess if no one instructs you how to care for your guitar then the natural assumption is that it is wood just like furniture and needs the same cleaners.
NOT!!!!!!

In addition to the above responses, there is a post in the FAQ section on this subject that you might find helpful.

Hi, thanks to all who replied - most interesting.  The threads in the FAQ are worth the read.
 
I bought a 150 mL (5 fl oz) bottle of lemon oil from a speciality foods shop.  It's made from crushed lemon peel and packed in Canton MA, see www.boyajianinc.com
 
Regards
 
Grant

That's the one I use.  I ordered it direct from the company and they also sent me a small sample bottle of wasabi oil, free of charge.
 
Bill, tgo

How did the wasabi oil work for your fingerboard?
 
Bradley

I bet it'd be great for hot licks!

The wasabi oil is perfect for raw wood! hehehehe
 
Bill, tgo

Thanks for that link, Lemon oil is on the way for my baby.  
 
Bill, you don't need Wasabi for your hot licks, just a kick-ass Further guitar...the one I've been following construction on for what seems like years.  I cannot wait to SEE it when it's done.  It's inspiring!

Thanks Roger.  It looks like the wait is almost over.  The last inlay took quite a bit of time to figure out how to do, but the result looks well worth the wait.  
 
Bill, tgo

Just found out The Body Shop has pure Lemon essential oil
 
 
Wu

On the same topic: I live in New Mexico and it's pretty dry here.  The thought of my ebony fingerboard drying up is a terrible one.  Anyone here that lives in a similar climate: how often do you soak your fingerboard in lemon oil?  Can you over-lemon it?

Don't think you can over oil it, the down side that if it was over oiled it would 'sweat' out of the wood and into the strings/fingers, maybe making the strings go 'dead' prematurely or make your fingers slippy,.
I guess if you live in a  hot dry climate 4 or more times a year is suficient, heated/air conditoned houses will have the same effect.
Then there is humidity, whilst I was on holiday in florida from the UK, I talked to a bass player who used a modulus if he played outdoor gigs as the humidity played havoc with his jazz bass neck.
There is a thread about it all somewhere here