I have a 20L plastic container full of filtered waste
oil mixed with partswashed kerosene, mounted up high, this travels down a copper pipe and then to a little potbelly stove, this is situated in the cnr of my shed with heat proof panels on the walls, and is a great way of free heating.
The design isnt approved by "treehuggers" or the environment council, and my recommendation on waste
oil burners is dont leave unattended.