If that butchers block oil does not have some sort of finish in it, such as varnish, lacquer etc. it is not giving you much protection. From what I have read the spar urethane is a good finish, I think the duck callmakers use it because of ease of use in dipping the calls. But I dip mine in diluted polyurethane, it works and is cheaper.
My choice is the Minwax Wipe On Poly, very little odor and fast drying. Lacquer is out of the question because of the fumes, tried it once and that was once too many. With the Wipe On Poly I can even put the finish on in the house which helps when it is cold or the wind is blowing. Today we had 40 plus MPH wind with a good dust storm, I just packed my toys and went inside and did my finish work at the kitchen counter. I do have a very understanding wife, she will even help with the callmaking when I ask.
Marvin