While the process for recycling oil varies by location, in California, residents take used motor oil to a collection center. Certified haulers gather the oil and take it to the recycling center. If gasoline, antifreeze or other liquids contaminate the oil, it cannot be recycled and must be disposed as hazardous waste.
In large industrial plants, oil is sometimes recycled on site by filtering and using it again. However, refiners insert some oil from collection sites into an oil refinery for the production of gasoline to fuel vehicles. Recyclers also reprocess oil from the collection site into clean lubricating oil. A last option is to burn the used oil as fuel to produce heat, although this is the least desirable type of use.
Processers treat the recycled oil to remove contaminants, and the product they produce meets standards set by the American Petroleum Institute. The process creates motor oil that all vehicle manufacturers approve for use in their cars that use standard oil. It has the same qualities as virgin oil and recyclers can continue to reprocess it indefinitely.
Recycling motor oil is less expensive than processing crude oil. While it takes 42 gallons of crude oil to produce 2.5 quarts of motor oil, one gallon of recycled motor oil produces the same amount and reduces the United States dependence on foreign oil.