Any oil that has been refined from crude oil, or any synthetic oil, that has been used and as a result of such use is contaminated by physical or chemical impurities is "used oil." Recycled used oil is regulated in 40 CFR Part 261.6(a)(4) regardless of whether or not it exhibits a characteristic. Used oil that can't be recycled and is disposed of or sent for disposal must be managed in accordance with all applicable solid and hazardous waste requirements. Check your state to see if your state is authorized for the Part 279 regulations.
40 CFR § 279.10(a), available at www.ecfr.gov
57 FR 41566, 41578; September 10, 1992
Waste Used Oil Frequent Questions
Monthly Call Center Report Question; November 1996 (RCRA Online 14054)
Memo, Pertruska to Citizen; October 13, 1993 (RCRA Online 11786)
To check your state:
Waste State Contacts