You know.. a centrifuge.. ;) Make the oil dizzy till it coughs up soot.
[h=3]cen·tri·fuge/ˈsentrəˌfyo͞oj/[/h]Verb: Subject to the action of a centrifuge.
Noun: A machine with a rapidly rotating container that applies centrifugal force to its contents, typically to separate fluids of different densities or liquids from solids.