Motor Oil and the Water Supply

• Oil stays on the surface of water.Paul Katz/Photodisc/Getty Images
  
  According to the Mississippi Department of Environmental Quality, it takes as little as 1 gallon of improperly disposed motor oil to contaminate 1 million gallons of water. Because oil floats on the surface of water, it reduces the amount of oxygen available in the water. This can kill aquatic plants that need oxygenated water to survive; it can also encourage anaerobic algae, which can choke out other aquatic plants, to form since they need no oxygen.
  
  

Motor Oil and Soil

• Because oil is meant to lubricate and penetrate, it seeps quickly into the soil. According to J. Kayode in "The Effects of Used Engine Oil Pollution on the Growth and Early Seedling Performance of Vigna Uniguiculata and Zea Mays," oil displaces air pockets in topsoil, which interferes with plant respiration. Similarly to oil-coated water, this reduces the amount of oxygen that can enter the soil, suffocating the plants. Oil can also penetrate all the way down to groundwater, further contaminating water supplies. While microorganisms and hardy plants can be used to clean oil-contaminated soil, the process can take years to complete.
  
  

Motor Oil's Poisons

• Combustion engines add many chemicals to used motor oil.Thinkstock/Comstock/Getty Images
  
  Motor oil contains many dangerous compounds that can kill plant and animal life. Most notably, motor oil contains a great deal of lead, which accumulates in the oil from contact with combustible fuels in engines. Motor oil also picks up heavy metals and carcinogens, and it contains other dangerous chemicals used to enhance its performance as a lubricant. These chemicals not only damage or kill plants but also cause cancer in animals and humans after prolonged exposure. James B. Willis, Jr. notes in "Proper Disposal of Used Motor Oil" that plants which survive living in oil-contaminated soil can contain concentrated amounts of these chemicals, poisoning the animals and humans that eat them.
  
  

Avoiding Oil Contamination

• Motor oil can be recycled.Comstock/Comstock/Getty Images
  
  You can avoid contaminating the soil and water supply with oil by using a reputable mechanic who disposes of or recycles oil properly. If you change your own oil, take your used oil to a collection site or a local mechanic rather than pouring it into storm drains or onto the ground. You can find a local oil recycling center at http://earth911.com/. If there is no oil disposal site close to you, consider organizing one to benefit your local community.