I know that most people here, including myself like to use only water on our sharpening stones, however I do know that some like to use a more viscous fluid such as honing oil. I could never figure this out as despite the theory you will always end up with a part clogged, gunk filled stone right from the first use and on forever! Many bushies in Australia use plain old dishwashing liquid on their stones instead of oil as this way the stones clean up very well with no oily gunk leftover! Just wash them in warm water after use! No need to add soap it's already in the stone!