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Used oil is produced in many service and industrial activities such as auto repair, metal working, machine lubrication, refrigeration, and hydraulic equipment repair. Used oil can be recycled to make new lubricants or used as an industrial fuel when properly managed. When recycled, used oil is excluded from regulation as a hazardous waste.

Recycling used oils prevent potential pollution of the air, land, surface water, and groundwater. Used oil can contain cancer-causing agents, metal contaminants, and organic compounds that filter into the groundwater supply when the used oil is dumped, spilled or sprayed as a dust suppressant. Such contamination can result in serious hazards to human health.

Used Oil Defined

Used oil is 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. Used oil must have been refined from crude oil or made from synthetic materials. Animal and vegetable oils are excluded from the definition of used oil.

Used Oil Includes:

  • Synthetic oil — usually derived from coal, shale, or polymer-based starting material.
  • Engine oil — typically includes gasoline and diesel engine crankcase oils and piston-engine oils for automobiles, trucks, small engines, boats, airplanes, locomotives, and heavy equipment.
    • Transmission fluid
    • Hydraulic fluid
    • Refrigeration oil
    • Compressor oils
    • Metalworking fluids and oils
    • Electrical insulating oil
    • Brake fluid
    • Greases

Used Oil Does Not Include:

  • Used oil mixed with hazardous waste(s)
  • Brake fluid contaminated with chlorinated compounds
  • Petroleum and synthetic products used as solvents
  • Antifreeze
  • Kerosene, gasoline, diesel or jet fuel
  • Vegetable and animal oil, even when used as a lubricant
  • Wastewater from which the oil has been removed
  • Oil contaminated media or debris
  • Oil contaminated with PCB's
  • Metalworking fluids formulated with chlorinated compounds

On-Specification and Off-Specification Used Oil

To qualify as on-specification used oil, the oil to be burned for energy recovery cannot exceed any of the following limits. In general, if your used oil is just crankcase used oil and not mixed with anything, it will be on-specification. If you choose not to test for the on-specification status, or do not have knowledge* of your used oil it must be managed as off-specification.

*Knowledge is personally knowing how the used oil was generated, where it came from and what sources of contamination are possible. Knowledge also includes making decisions on new batches of used oil based on testing results of previous batches.



Allowable On-Spec Level

Analytical Test

Arsenic 5 ppm maximum SW-846, Methods 3040/3050
Cadmium 2 ppm maximum SW-846, Methods 3040/3050
Chromium 10 ppm maximum SW-846, Methods 3040/3050
Lead 100 ppm maximum SW-846, Methods 3040/3050
Flash Point 100°F minimum SW-846, Method 1010
Total Halogens (rebuttable presumption) 1,000 ppm SW-846, Method 8021
Total Halogens 4,000 ppm SW-846, Method 8021

NOTE: Used oil containing more than 1,000 ppm total halogens is presumed to be a hazardous waste. Persons may rebut this presumption by demonstrating that the used oil does not contain hazardous waste by using an analytical method from SW-846. For test methods that may be used for the rebuttal, see the EPA's Method 9076 and Method 9075 (September 1994).

Used Oil Generators

A used oil generator is any person, by site, whose act or process produces used oil or whose act first caused the used oil to be regulated.

Generators are businesses that handle used oil through commercial or industrial operations or from the maintenance of vehicles and equipment. Examples of common generators are car repair shops, service stations, quick lube shops, government motor pools and other government agencies, grocery stores, metalworking industries, and boat marinas.

Used oil regulations do not apply to:

  • Individuals who generate used oil through the maintenance of their personal vehicles and equipment.
  • Farmers who produce less than an average of 25 gallons of used oil per month from vehicles or machinery used on the farm during a calendar year.

Best Management Practices

  • Use labels and signs to segregate used oil from other wastes at your business and train your employees of the importance of keeping wastes separate.
  • Store used oil in a leak-proof, closed container.
  • Drain and collect all oil on a covered and curbed, impermeable surface area away from drains.
  • Do not open, handle, manage, or store containers and tanks in a manner that may cause them to leak or rupture.
  • Use tanks and containers that are in good condition (no rust, structural defects, or deterioration) to store used oil.
  • Be prepared to stop, contain, and clean up any releases of used oil.
  • Take steps to prevent the accidental contamination of your used oil with small amounts of solid or dangerous waste.
  • Label containers, aboveground tanks, and fill pipes with the words, "Used Oil."
  • Physically inspect all used oil storage containers and tanks on a regular basis.
  • Know the on-spec/off-spec status of your used oil before it leaves your site.
  • Know whether your used oil is prohibited from burning as used oil prior to it leaving your site.
  • Know how your used oil will be recycled before it leaves your site.
  • If possible, keep all containers stored inside or under cover.

Recycling or Disposal of Used Oil

Recycling Used Oil

Used oil can be recycled in the following ways:

  • Reconditioned on site, which involves removing impurities from the used oil and using it again. While this form of recycling might not restore the oil to its original condition, it does prolong its life.
  • Inserted into a petroleum refinery, which involves introducing used oil as a feedstock into either the front end of the process or the coker to produce gasoline and coke.
  • Re-refined, which involves treating used oil to remove impurities so that it can be used as a base stock for new lubricating oil. Re-refining prolongs the life of the oil resource indefinitely. This form of recycling is the preferred option because it closes the recycling loop by reusing the oil to make the same product that it was when it started out, and therefore uses less energy and less virgin oil.
  • Processed and burned for energy recovery, which involves removing water and particulates so that used oil can be burned as fuel to generate heat or to power industrial operations. This form of recycling is not as preferable as methods that reuse the material because it only enables the oil to be reused once. Nonetheless, valuable energy is provided (about the same as provided by normal heating oil).

Sending Used Oil Off-Site

The following is a list of acceptable places where generators can send used oil:

  • A facility that has notified Ecology as an off-specification used oil burner.
  • A facility with a boiler, industrial furnace, or space heater that accepts on-specification used oil.
  • A used oil collection center.
  • A facility that has notified Ecology as a used oil processor.
  • Another business site you own that may have a space heater if that site complies with the aggregation point requirements in the regulations.

Handling Used Oil


  • Label all containers and tanks as Used Oil.
  • Keep containers and tanks in good condition. Don't allow tanks to rust, leak, or deteriorate. Fix structural defects immediately.
  • Never store used oil in anything other than tanks and storage containers.
  • Containers must be closed at all times, except when adding or removing used oil.
  • Containers and tanks must not be opened, handled, managed or stored in a manner that may cause the container or tank to leak or rupture.
  • Thurston County requires all containers or tanks of used oil and product oils to be stored in approved secondary containment. For additional information, see Secondary Containment.


In Thurston County, your business' options for used oil management consist of: shipping off-site to be recycled, recycling on-site in an approved EPA approved waste oil heater, recycling through Thurston County’s hazardous waste collection site at HazoHouse, or disposing it as a hazardous waste through a hazardous waste vendor.

As a generator, if you transport more than 55 gallons of used oil, you must deliver the shipment to an approved used oil collection center. The center must collect and retain the following information about you: your name, address, telephone number, date of delivery and amount being delivered.

For a list of oil collection centers and used oil transporters in Washington State, see WA State Dept of Ecology, Hazardous Waste Services Directory.

Burning used oil in EPA approved waste oil heaters

Used oil generators may burn used oil in on-site space heaters provided that:

  • The heater burns only used oil that the owner or operator generates themselves or used oil received form household “do-it-yourself” used oil generators.
  • The heater is designed to have a maximum capacity of not more than 0.5 million BTUs per hour.
  • The combustion gases are vented to the outside air.
  • The burner is operated following the manufacturer’s specifications.

Mixing used oil

No solid waste or hazardous waste can be mixed into or with used oil. If this occurs, the mixture is no longer considered used oil, and could be a hazardous waste (the entire contents of the container or tank. Examples of the types of wastes that cannot be mixed with used oil include solvents, paints, inks, “cleaners,” and plastics.

Legitimate unused fuel products, such as gasoline, kerosene, diesel, or Jet-A fuel may be added to used oil if the mixture is to be burned for energy recovery. An example would be gasoline that was drained form a car at an automobile recycling facility and added to used oil. Mixing gas, kerosene, or other fuels with used oil may produce a “rich mixture” that may present safety issues when burned in a space heater.

Oil Leaks and Spills

  • Take steps to prevent leaks and spills. Keep machinery, equipment containers, and tanks in good working condition and be careful when transferring used oil. Have absorbent materials available on site.
  • If a spill or leak occurs, stop the oil from flowing at the source. If a leak from a container or tank cannot be stopped, place the oil in another holding container or tank.
  • Contain spilled oil. This can be accomplished by placing absorbent berms around the spill or by spreading an absorbent over the oil and surrounding area.
  • Clean up the oil and recycle the used oil as you would have before it was spilled. If recycling is not possible, you first must make sure the used oil is not a hazardous waste and dispose of it appropriately. All used cleanup materials, from rags to absorbent booms, that contain free-flowing used oil also must be handled according to the used oil management standards. Remember, all leaked and spilled oil collected during cleanup must be handled as used oil. If you are a used oil handler, you should become familiar with these cleanup methods. They may also be part of a spill response action plan.
  • Remove, repair, or replace the defective tank or container immediately.

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This page last updated: 08/12/22