Greetings Mancavebuilder! Glad you stopped by!
Interesting question on the Efel stove. I dont think I have ever heard of anyone using one with waste oil, but it would be interesting to see if it would work.
Enjoy the forum. It is more of an archive of info than a thriving discussion spot, but even still, there is some good info out here.
If you end up doing anything, please let us know!
Good luck!
Russ