Well here are some other thoughts....

The only way to use used motor oil in a manner that is safe for the engine would be to run it through a fractionation process again. That would get rid of the metal particulate content and soot.

If someone wanted to hire a lawyer they could make a couple of arguments in court (Not that a judge would buy it).

For legal purposes road tax wise used motor oil could be considered an additive just like 2 stroke motor oil. Additives are exempt from road taxes. Can anyone find a law that limits the amount of additive that is added to ones tank?

Secondly all internal combustion engines burn a little oil and are certified by the EPA as doing such. If your engine can burn the oil and pass an emissions check your in the clear. Is there any regs on adding additives to your fuel before an emissions check?

__________________
green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png