When it's switched on the heat will warm up the wax, which rises to the surface, by the time it's getting to the surface, that wax is cooling down so it wil start decending again, warming up again as it gets nearer the bottom.
The wax and the oil are insoluable in one another.
But we all acquire our knowledge from somewhere, Laki.
You remembered it, so you are clever.
(no posts please about whether intelligence can consist merely of a substantial capacity for recollection, or does it require an element of analytical input)