Automotive oil recycling

[2][3] Recycled motor oil can be combusted as fuel, usually in plant boilers, space heaters, or industrial heating applications such as blast furnaces and cement kilns.

The used oil is first tested to determine suitability for re-refining, after which it is dehydrated and the water distillate is treated before being released into the environment.

Dehydrating also removes the residual light fuel that can be used to power the refinery, and additionally captures ethylene glycol for re-use in recycled antifreeze.

[6][7][8] The sludge ("residue") associated with engine oil recycling, which collects at the bottom of re-refining vacuum distillation towers, is known by various names, including "re-refined engine oil bottoms" (abbreviated "REOB" or "REOBs").

[9] A report from the U.S. Federal Highway Administration (FHWA) states that: Some producers of asphalt for paving have—openly or secretly—incorporated REOBs into their asphalt, creating some controversy and concern in the traffic engineering community, with some experts suggesting it reduces the durability of the resulting pavement.