There is no good reason to ever use mink oil on dress shoes, or even casual shoes for that matter, and lots of reasons not to. I suppose one could use it on hiking boots or the like, but beyond that, no, no, no. First, shoe leather doesn't need this waterproofing. It's already waterproof! Second, mink oil will invariably darken leather and make it harder to achieve a really nice built-up finish via the usual process of shoe cream and shoe polish. There's just no reason whatsoever to ever use it on shoes. To maintain waterproofness in the seams of shoes, any good polish that contains wax (and even some creams) rubbed into the leather and the gap between the uppers and welt (or top of the outsole) will be more than sufficient. For leather nourishment, I sometimes use a good leather conditioner, like the Allen-Edmonds one first before polishing. This will keep the leather supple and preventing cracking. Then I apply cream (I use the Collonil line) to restore any color lost through scuffs, etc., and to further nourish the leather. Either the leather conditioner or the shoe cream (usually in tubes or jars) or both will provide all the moisterizing that your shoes will ever need and will keep them supple and soft. I finish off with a polish--by which I mean a product, usually in a can, not a jar, that contains wax, usually Carnauba wax. This provides excellent protection against the elements. Forget mink oil.