Your problem maybe adhesion?
Do your sample on top, as the bottom is not "aged" unless you want to use the bottom as the top. You want to make sure whatever coating you descide to use that it gets good adhesion, oil can be a tough canidate for good adhesion unless you remove it.
Cadidz, If I knew what it was, I would have told you in the beginning.
With your new photo, you should find out soon.
Good Luck
What kind of oil was used?
Cazdids,
Was is determined if the "oil" on the table was a drying or non drying oil to start with, and are you down to the raw wood now.
Neil, was right when he said, it was not OAK, so he will always be half right.
Caz, do an Internet search for photos of those that were already mentioned, you might get lucky and find your answer.