I only clean non valuable coins. For IHP's I used warm soapy water and a soft bristled tooth brush. Once they dry I do a dry cleaning with toothpicks in order to get into the nooks and crannies. this leaves the patina, I am certain it will work on wheats also. If there are any large encrustations on the coin, I recommend a soak in the oil. I prefer mineral oil since it does not darken the coin as much as EVOO.