Alan, Joe's suggestion sounds a bit more practical IMHO.
I know your one heck of a talented guy.
Casting Metals In Your Backyard But you want to put together a home made induction heater to heat a flammable product in the house that you and your family sleep in?
Perhaps something a little more conventional in the home?
I got to help repair the fire damage in a animal fat refinery where a pipe burst that was filled with pressurized hot animal fat. It worked like a flame thrower until the pumps where shut down.
I can imagine that if you accidentally overheat the vegetable oil you could burst a pipe and have instant ignition of the oil.
Good luck no matter what you do.
Bob