Any kind of food grade oil will work as a pre-shave oil, even olive oil.So one needs a high quality brush and soap AND is limited to a single edge razor in order to be successful? No compromise. Yet we can agree that my leftover sardine oil is a valid base for a preshave routine? Ummm... Guffaw.
I suggest that you look at the ingredient list for a typical pre-shave oil.
Also meant to say "single blade" not "single edge" razor.