Per bsmith_shoot's photo of the Kasco Corp "Super Sharp" food grade lubricating oil, the FDA CFRs listed pertain to "white mineral oil", so that's another vote for mineral oil. Their version may have some antioxidants in it. Mineral oil is widely available, and widely sold as butcher block and wooden knife handle oil by restaurant supply stores. But if you keep your knives dry, you probably don't even need that. Just my $0.02.