I have a round titanium tank (true) which I used to put on an off the shelf hot pad, in which I would boil (about 120 degrees) a stock in tricloroethelyn (spelling?) for about 15 - 20 minutes.
Very environmentally unfriendly, I'm afraid. You have to do it outside and be sure not to breath the fumes (extremely caustic).
That stuff is a non-flameable dry cleaners cleaning solvent. You used to be able to buy it off the shelf at hardware stores, but it hasn't been available that way for years.
The heat helps bring the oil to the surface which is immediately leached off. It helps get oil out of the interior of the wood, not just the top surfaces.
