you could not do that here
Since its implementation on January 1, 1987, California's Management of Used Oil Act (SB 86) has prohibited the disposal of used oil by discharge to sewers, drainage systems, surface or groundwaters, water courses or marine waters, by domestic incineration or burning as a fuel, or by deposit on land, unless otherwise authorized by law
but they are right, 1/2 of it is burned, after they filter out the heavy metals.
http://www.synlube.com/usedoil.htm#Why%20is%20Used%20Oil:%20"Hazardous%20Waste"?
big long diatribe on it from 8 YEARS ago, since then there are more advancements.
(note: i am not advocating thier lube, nor do i think its claims are valid)
basically because LUBE oil is ONE of the things made from crude, that is plentifull compared to the almighty gasoline, Lube from Crude is more a BY-Product than a money maker.
so putting lube oil "back into a cracker", as crude would, isnt going to get them the $$$ so its off to the trash with it.