Tunong pins are basically "press fit" and rely on the hole size being maintained. Although oil might swell the wood to some degree, in the end it will absorb into the wood and the pin will have no bite. You drill a 15/64" hole for a 1/4" tuning peg and then hammer (not screw) the tuner in about halfway. Then you screw it down a few turns. This roughens the sides of the hole and cuts threads in the wood. This is obviously a close fit, but one which can easily be ruined by oil soaking into it, or manhandling the tuning pegs with an L-Shaped wrench (a T-handle is best.....and if you can find a bunch of old clock keys, some of them are very attractive and will fit.