Waste Programs Division: Solid Waste Management: Used Oil

Used Oil Specifications

Most used oil in Arizona is burned as a substitute fuel for energy recovery. Because it has been used, used oil may contain many more contaminants than virgin oil. Because it may contain more contaminants in higher concentrations than virgin oil, there is a potential that more contaminants could be released into the atmosphere from burning used oil, than from burning a virgin oil or other cleaner-burning fuel.

The U.S. EPA has determined that only certain contaminants pose significant threat to public health or the environment. As a result, the U.S. EPA has established limits for the maximum concentrations for the contaminants of concern. These limits were set such that the emissions from burning used oil containing these contaminants, at or below these limits, will pose no more threat to public health or the environment than the emissions from burning a cleaner-burning fuel, such as virgin oil or diesel.

The maximum contaminant concentrations, including a limit on the minimum flashpoint (a safety consideration) that a used oil fuel may have, are referred to as the used oil specifications.

Used Oil Specifications
Constituent/PropertyAllowable Level
Arsenic*5 ppm or less
Cadmium*2 ppm or less
Chromium*10 ppm or less
Lead*100 ppm or less
Flashpoint100° or more
PCBsless than 2 ppm
Total Halogens**1000 ppm or less

* Note: This specification is for Total Metals, not Total Characteristic Leaching Procedure (TCLP).
** Note: Only for total halogen concentrations 1000 ppm or more for which the presumption of mixing has been successfully rebutted.

Used oil that meets all the specifications is referred to as on-specification used oil. Used oil that does not meet all the specifications is referred to as off-specification used oil, except when either of the following two conditions apply:

  • PCBs are 50 ppm or more: This used oil is regulated as a toxic waste under the Toxic Substance Control Act (TSCA), or 40 CFR 761.
    • For more information about when used oil is regulated as a TSCA waste, refer to When Used Oil Is Regulated as a TSCA Waste.
  • Total Halogens exceed 1000 ppm: This used oil may be regulated as a hazardous waste under 40 CFR, Parts 260 through 266, 268, 270, and 124.

In Arizona, an air quality permit is required any time burning is to take place in a commercial or industrial application. Among other things, the air quality permit will specify which fuels may be burned and the maximum contaminant emissions allowed. Permits which allow burning used oil typically specify the cleaner-burning on-specification used oil. If a facility were to elect to burn off-specification used oil, it would have to demonstrate that it is capable of cleaning up the resulting emissions to meet applicable air quality standards.

For more information about air quality permits in Arizona, contact the following agencies:

When Used Oil Is Regulated as a Hazardous Waste

Used oil often contains halogens, many of which are listed hazardous wastes. In many instances, the presence of halogens in the used oil is the result of mixing with chlorinated solvents. The U.S. EPA has determined that used oil containing 1000 ppm or less total halogens is not a hazardous waste. Used oil containing 4000 ppm total halogens is a hazardous waste subject to regulation under 40 CFR, Parts 260 through 266, 268, 270, and 124. For used oil containing total halogen concentrations between 1000 ppm and 4000 ppm, the U.S. EPA has said it must be presumed that the used oil has been mixed with a list halogenated hazardous waste, but the U.S. EPA allows the used oil handler to rebut the presumption of mixing, by demonstrating that the used oil has not been mixed with a listed halogenated hazardous waste. The demonstration may be made by testing the used oil with an analytical method from SWS-846, Edition III, such as U.S. EPA Method 8021, or by applying knowledge of the halogen content of the used oil in light of the materials and processes used.

The Rebuttable Presumption

This concept of presuming that used oil containing more than 1000 ppm total halogens may be a hazardous waste by virtue of having been mixed with a listed hazardous waste, and that this presumption may be rebutted by showing that it does not contain hazardous waste, is referred to as the rebuttable presumption. The rebuttable presumption applies to any regulated used oil handler in possession of used oil with a total halogen concentration above 1000 ppm.

When Used Oil is Regulated as a TSCA Waste

Although PCBs have been banned for most applications, they are still occasionally encountered. PCBs are regulated under the federal regulations for the Toxic Substance Control Act (TSCA) at 40 CFR 761. How used oil containing PCBs is regulated depends upon the concentration of PCBs in the used oil. Used oil containing less than the quantifiable level of 2 ppm PCBs is not regulated as a TSCA waste, but rather as used oil under 40 CFR 279. Used oil containing 50 ppm or more PCBs is regulated as a TSCA waste. For used oil containing PCB concentrations of 2 ppm or more, but less than 50 ppm, TSCA requires the used oil to be handled in the same manner as off-specification used oil. However, if the used oil is to be burned, the PCBs must be completely destroyed.