A great home made leather conditioner is equal parts of beeswax and neatsfoot oil. Heat the beeswax and neatsfoot oil in an empty tin can to mix them. This concoction is also great for softening and waterproofing leather boots. I use a brush to apply it to the leather and seams of boots while the mixture is still quite warm so it penetrates deep into the leather. Buff off any excess after it sits awhile. Naturally, this will darken old dried out leather, same as plain neatsfoot oil. I get my beeswax from a local bee keeper. I used to use wax toilet bowl seal rings, but they are now made from a synthetic substitute.
