Rustoleum Watco Teak Oil Finish. Hardens in the wood, not on the wood. Specially formulated for dense woods such as teak, mahogany, and rosewood. Unlike surface coatings, WATCO penetrating oil enhances the natural look and feel of wood. It penetrates DEEP into wood pores to create the rich, warm glow of a hand-rubbed finish. WATCO Teak Oil protects wood from within, It will not chip, peel, or wear away.