I made one of the waste oil heaters from an old water heater tank, and need to get it fired up again with a dedicated chimney. Look at the old Mother Earth News links for plans.

One of the guys here who is a Master Tinkerer and Restorer of All Things (Mike P) explained one time the details of his little converted wood burner to waste oil, including a storage tank and waste oil hauler so he could collect from some of the locals. I found one picture of the converted stove, but the details aren't in this thread, which covers his '30s' shop pieces & parts, many recovered from the family property - My 1930's Farm Shop

I expect if you ask Mike would point to the earlier explanation, or maybe do a new thread?