On-spec and off-spec used oil
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 Resources: Used Oil Management
September 21, 2017
On-spec and off-spec used oil

In a recent, brief letter, EPA’s Office of Land and Emergency Management (formerly Office of Solid Waste and Emergency Response) indirectly informed a recycling association that it would not grant the association’s request to modify the Agency’s regulations regarding on-specification (on-spec) and off-specification (off-spec) used oil (EPA’s letter is here).


The association specifically asked that the EPA modify its description of off-spec used oil fuel burned for energy recovery to exclude the flashpoint criterion and thereby allow off-spec oil with a flash point below 100°F to qualify as a nonhazardous secondary material (NHSM) under 40 CFR Part 241. The EPA simply replied that under 40 CFR Section 279.11, any used oil with a flash point below 100°F meets the hazardous waste characteristic for ignitability (i.e., flash point is below 140°F) and, therefore, is “outside the scope of the NHSM regulations.

While used oil can be off-spec and, therefore, a hazardous waste, it can also be a valuable fuel. To promote recycling while not allowing unregulated disposal of hazardous used oil that can pose a risk to human health and the environment, the EPA developed a complex set of management requirements at 40 CFR part 279; regulations directly affecting off-spec oil are at Part 279, Subpart G.

The request and EPA’s response offers an opportunity to explain the differences between on-spec and off-spec used oil.

Types of used oil

In general, used oil includes motor oils, greases, emulsions, machine shop coolants, heating media, brake fluids, transmission fluids, other hydraulic fluids, electrical insulating fluids, metalworking fluids, and refrigeration oils.

Used oil does not include fuel product storage tanks’ bottoms, fuel product spill cleanup material, other waste that results from oil that has not been used, animal and vegetable oils and greases, antifreeze, and materials used as cleaning agents or only for their solvent properties.


In addition to the flash point requirement, a used oil is considered on-spec and not subject to Subpart G, when burned for energy recovery if it does not exceed the following constituent levels:


Allowable level
(parts per million)









Total halogens


Rebuttable presumption

Also, the EPA considers used oil containing more than 1,000 parts per million (ppm) total halogens to be a hazardous waste because the Agency presumes the used oil has been mixed with halogenated hazardous waste. However, Section 279.10 provides that the presumption that mixing has occurred may be rebutted. To rebut the presumption, persons would need to demonstrate through analysis or applied knowledge that the used oil does not contain significant concentrations of halogenated hazardous constituents. For example, an analysis would be used to identify which materials are contributing to the higher total halogen value. EPA method SW 846 is one type of analysis that can be used to show that the used oil does not contain significant concentrations of halogenated hazardous constituents. Use of product safety data sheets (SDS) and/or knowledge of the process used to create the waste can qualify as applied knowledge. Bear in mind that ingredients of less than 1 percent (or 10,000 ppm) are not typically required to be reported on an SDS.

Additional on-spec/off-spec points

  • Off-spec used oil fuel may be burned for energy recovery in only the following devices (subject to conditions listed in Section 279.61):
    • Industrial furnaces
    • Industrial boilers located on the site of a facility engaged in a manufacturing process where substances are transformed into new products, including the component parts of products, by mechanical or chemical processes
    • Utility boilers used to produce electric power, steam, heated or cooled air, or other gases or fluids for sale
    • Used oil-fired space heaters
    • Hazardous waste incinerators.
  • The rebuttable presumption does not apply to metalworking oils/fluids containing chlorinated paraffins if they are processed, through a tolling arrangement as described in  Section 279.24(c), to reclaim metalworking oils/fluids. The presumption does apply to metalworking oils/fluids if such oils/fluids are recycled in any other manner or disposed.
  • The rebuttable presumption does not apply to used oils contaminated with chlorofluorocarbons (CFCs) removed from refrigeration units where the CFCs are destined for reclamation. The rebuttable presumption does apply to used oils contaminated with CFCs that have been mixed with used oil from sources other than refrigeration units.
  • A generator, transporter, processor/rerefiner, or burner that first claims that used oil that is to be burned for energy recovery is on-spec must keep copies of analyses of the used oil (or other information used to make the determination) for 3 years.
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