As a non-technical party, thank you for allowing me to ask the following question of your serious-minded community: I recently found a parlor-style, 70’s, Mitchell; although low-end, its unique Ovation-style back makes it perfect in contour, in regard to spinal issue. Could a light oil or perhaps Murphy Oil Soap be used inside the sound box without causing glue deterioration or wood damage? Sound alteration is secondary to preventing splitting. (Managing humidity, via introducing a humidity releasing process, is not practical for me.) Overall, the instrument is in very good condition, but a superficial crack on face concerns me about the internal condition that might show effect in years to come. I am most grateful of community comment of any damaging effect of oils or Murphy Soap on glue or wood—Jeff.