Salt cannot dissolve in oil. This is because salt is a non-polar substance, because it's bonds are non-polar (this is not to say though that polar bonds always means its a polar substance, but that's another issue). Oil is a polar substance (meaning one end of its molecule is has a slight negative charge, the other a slightly positive charge. It is known that LIKE dissolves LIKE. (e.g. Polar dissovles Polar). There are VERY few exceptions to this.