I use camellia oil. It's what is used traditionally on Japanese swords and cutlery. The benefit is that it's organic and doesn't go rancid like other oils. Mineral oil is good too though. I just oil the edge, not the whole knife.
To prevent rust on the rest of the blade, I allow a natural...
I've written a tutorial on this subject that is based on the Edge Pro sharpening system. But it can be adapted easily to any other angled sharpening system.