Over time, the oil that lubricates motors -- whether in cars, boats, lawnmowers or farm equipment -- picks up impurities. These impurities limit the lubricating properties of synthetic and petroleum-based oils, and ultimately, they must be replaced with new motor oil. (See Reference 1) Any time used motor oil escapes from an engine crankcase, it has the potential to pollute the environment.
From Engine to Environment
You have probably seen a dark spot on a concrete driveway or the oily sheen of a parking-lot puddle. According to the U.S. Coast Guard Emergency Response Notification System, used motor oil is the most commonly spilled type of oil in the U.S. (See Reference 2, page 6) The Massachusetts Department of Environmental Protection reports that Americans spill 180 million gallons of used oil per year, most of which ends up in waterways. (See Reference 6).
A Cocktail of Toxins
Used motor oil contains numerous toxic substances, including polycyclic aromatic hydrocarbons, which are known to cause cancer. In addition, tiny pieces of metal from engine wear and tear, such as lead, zinc and arsenic, make their way into lubricants, further contributing to the polluting potential of used motor oil. Motor oil is exposed to heat and oxygen during engine combustion, which changes its chemical makeup. (See Reference 2, Pages 6 and 7) Because spent motor oil is heavy and sticky, and contains an extensive concentrated cocktail of toxic compounds, it can build up and persist in the environment for years. (See Reference 1).
Soil and Water Pollution
Once motor oil escapes the engine, it has the potential to travel long distances, and most used motor oil eventually makes its way into waterways in the form of runoff. (See Reference 5, Page 5) Once it reaches waterways, used motor oil is toxic to plants and animals living in the water, and its film can impair natural processes, such as oxygen replenishment and photosynthesis. (See Reference 3) Used motor oil can also pollute soil and drinking water. According to the U.S. Environmental Protection Agency, 1 gallon of used motor oil can contaminate 1 million gallons of fresh water. If used motor oil reaches sewage treatment plants, even small amounts -- 50 to 100 parts per million -- can foul the water treatment process. Soil becomes less productive when exposed to used motor oil. (See Reference 3)
Preventing used motor oil from entering the environment is not difficult. Many municipal recycling centers have used-oil disposal stations. Although an estimated 800 million gallons of used motor oil are recycled annually, millions of gallons are still disposed of improperly. (See Reference 4, page 1) Utilize a designated oil-disposal facility to avoid incorrect -- and in most cases illegal -- disposal methods. Never dispose of used motor oil in the trash, down household drains, into storm drains or directly onto soil. Inspecting equipment and vehicles regularly and immediately repairing items that appear to be leaking oil is another way to prevent pollution from used motor oil.
- EPA: Used Oil Management Program
- National Park Service: Environmental Contaminants Encyclopedia
- EPA: How to Setup a Local Program to Recycle Used Oil
- Environmental Engineering Science: Phytoremediation of Soil Contaminated with Used Motor Oil
- California Environmental Protection Agency: Characterization of Used Oil in Stormwater Runoff in California
- Massachusetts Department of Environmental Protection: Nonpoint Source Pollution Education -- Motor Oil
Jennifer King has written and edited since 1994, and now works as a business technical writer. Her articles appear on GardenGuides, eHow and LIVESTRONG.COM. King has a Bachelor of Arts in English, a minor in Latin American and Caribbean studies, coursework in yoga and certifications in nutrition and childhood development.
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