Depends
The ones I use the most are Norton (aluminum oxide?)
dual sided stones. They don't get anything. After 10
or 12 uses they get washed off with dish liquid and
scrubbed with an old toothbrush. They look brand
new afterwards. The arkansas stones get water or
whatever is handy. I used to keep one at work, and
use in one of the parts washers with the solvent
squirting out of the spout. I'm pretty sure it's just
mineral spirits. Probably the best liquid I've used
with a stone. Better than any oil I've used
