My project camera is a 1913 Graflex 3-A that's seen better days.The leather is dry and detached in many places.One product that was suggested to me was "Neatsfoot Oil" and it works like a charm.Makes the Graflex's skin nice and supple and so much earier to work with.I also tried it on some old leather straps & cases with impressive results.
My APUG search turned up one mention of the product and that was in 2005.Neatsfoot oil is readily available at your local shoe repair shop and easy to use.