Winter before last I burned it in my woodfurnace up in the old shed with a drip setup I fabbed up. I've since replaced the woodfurnace with a doublebarrel stove cause the furnace was just too nice to be in the shed ..... moved it down to the house. So I've been storing waste oil in a 55 gallon drum which is now full ....... so I need to start another. Eventually I would like to either find a proper waste burner or make one up myself to use as supplemental heat in the new polebarn.
My oldest kid does his own oil changes on his fleet of delivery vehicals ..... with his six trucks, plus his two cars, our two vehicals, and the tractor, ZTR, etc. it seems to accumulate fairly fast here. No sense wasting a free fuel source .... providing ya have enough of it to make it worth messing with.