Some commercial bowl makers use plain mineral oil. Nut oil, olive oil, vegetable oils will turn rancid eventually. However, if the bowls are used frequently, olive oil would work as well as anything, and it's safe. Many folks are allergic to nut oils. Old Joe Joe Brott, Plattsmouth, Nebraska www.oldjoe.org Len Dillon Roughouts & Turnings: www.diamondd.org