I attended a sharpenning class by a fellow that did a sharpening seminar for a bonsai club. He said to never use oil, only water. Immerse the stone in water until the small bubbles stop coming out, then sharpen, keeping the stone as wet as possible, rinsing frequently. He further said that if you had used oil in a stone previously, you should throw it in a fireplace to burn all the old oil out then start to use water. I have sharpened my kitchen knives this way for a while now and it seems to work fine for me. Cheers.