The idea wood should be oiled on a wind instrument might seem unusual at first but it is rooted in the understanding that wood changes size depending on many forces. Temperature, and moisture are the two most pronounced ways wood changes in size. Moisture offers the threat of cracking wooden wind instruments far more then temperature does (and the opposite is true for string instruments). The idea of oiling wood then comes down to the ability to block moisture from absorbing into that wood and keeping the wood in a permanently swollen state which aids in preventing cracks or stresses in the wood while being stored and played.

This is where things become increasingly confusing, as oiling wood is not equal with all oils