Ditto, ditto, ditto on the neatsfoot oil. A product is sold called neatsfoot compound but the oil works much better. I've read a few recommendations that the oil be applied to the flesh side preferably, but in some cases this can't be done. I have an old Air Force bomber jacket, Korean War vintage, with the original decals on it that I have kept going for years with the neatsfoot oil. With the lining sewn in, I have to apply it to the outside. It still works well though as Mart said, it will darken it slightly.