Watch out for toxic fumes when burning waste oil. No prob outdoors, just remember
that there is a lot of trace metallic contamination and various metal oxides can be hard
on you.
Lots of free energy there. Saw a design for a waste oil atomizer that was totally clog proof
years ago. 1-2 inch hollow metal sphere with a overflow collection cup draining back to oil reservoir
and a feed line dribbling a moderate stream of oil on top of the sphere. A slot cut about 20% of
the equator, and the sphere is fed high pressure air (seems like 30-40 psi, but a LONG time ago)
form the lolipop hollow support. The oil that runs over the slot gets atomized into very fine mist,
shot into a short tube into combustor.
Seemed like a neat idea, never built one, but if you are looking for a homemade atomizer design,
might try it.
Bill