How Does Motor Oil Affect Plants?

Motor oil poisons plants. This common lubricant may keep our car, truck and motorboat engines running smoothly, but it can cause a great deal of damage to plants and their surrounding ecosystem. Spilled or dumped motor oil contaminates plant life through soil or water, adding hazardous chemicals that are then passed on to plants, animals and eventually humans. Careful handling of used motor oil, and possibly the development of safer oils, can reduce environmental damage.

Properties

• Motor oil, a slippery fluid refined from crude oil, lubricates gas-combustion engine parts to prevent wear that might lead to breakdowns. As it performs its task in an engine, it picks up various toxic metals such as arsenic and lead, growing increasingly poisonous before it is finally discarded. According to Margo Reid Brown of the California Integrated Waste Management Board, "Used motor oil poses the greatest environmental risk of all auto fluids."

Effects

• Discarded oil does not degrade or dissipate. It leaches into soil and finds its way to bodies of water, contaminating the plants that depend on those resources to live. The contaminated plants then contribute trace amounts of these toxins to humans or animals who eat the plants. The Kentucky Division of Waste Management lists "lethal toxicity to plants and animals" as a direct consequence of improperly discarded oil, noting that some of this oil is deliberately dumped onto weeds to kill them.

Findings

• Studies have confirmed the effects of this contamination on plants' growth and reproduction. A study published by Environmental Engineering Science demonstrated that a mere 1 percent concentration of motor oil in soil reduced most seeds' ability to sprout, with green beans, corn and soybeans faring slightly better than other tested varieties. A California Agriculture report on oil's effectiveness as an insecticide states that oil is deadlier than water-based insecticides because "the film may creep from 4 to 6 inches down the stems and and kill all tissue from which new shoots might grow."

Prevention/Solution

• Vehicle owners can take steps to ensure that their used motor oil won't contaminate plants or other wildlife. The Center for Ecological Technology recommends returning used oil to the original place of purchase or to the local hazardous waste collection site. Recycled oil works just as well as unused oil at protecting car engines from wear. California, Massachusetts and Rhode Island classify used oil as a hazardous substance requiring special treatment.

Alternatives

• Some motor oils, such as Green Earth Technology's G-Oil, claim to be biodegradable. Made from tallow, a natural fat derivative, G-Oil can be combined with a second Green Earth product that breaks it down into a substance microorganisms can consume. But while the altered product itself may pose no risk to plants, the used oil could still contain traces of dangerous chemicals from the vehicle's engine.