European( read German) stock makers very often submerged new stocks in a barrel or vat of oil( linseed oil), until it absorbed all the oil it would take. Often times, this oil had coloring agents to darken the wood. This oil will not severely harm the wood, unlike petroleum based oils that may have soaked into the head of the stock over the years. It is understandable that efforts to remove all oil are very difficult and time consuming. It is not clear that removing a lot more than the petroleum based oil is absolutely necessary. I'm not trying to start a fight.
Mike
