There is a product called BOESHIELD T-9 which actually does, reportedly, work for this. It was suggested in some thread years ago and I got a can, it appears to work well enough keeping rust creep off my ancient drill press table.

Great to see Boeshield in this thread - so much of what's happening in this thread is the wrong product for a particular application. As you point out, Boeshield is a great product for protecting cast iron