Nicola,
Oracle is not supported at this time and there's no plan to support it in the near future.
I don't have access to an Oracle instance and when I looked at what it would take to support Oracle it would have required a bit of rework to do it cleanly. The reality is that not many people have asked for it and we very rarely use it on projects at Carbon Five, so there hasn't been much reason to spend the time on it.
Thanks for asking. Maybe one day I'll have the time (and a good reason) to add Oracle support.
Cheers,
Christian