Is it better for the environment to burn synthetic oil or conventional oil in my car’s engine?

Is it better for the environment to burn synthetic oil or conventional oil in my car’s engine?

—David Bedell, New Canaan, CT

According to the Pennsylvania Department of Environmental Protection, 85 percent of the motor oil changed at home by do-it-yourselfers—about 9.5 million gallons a year in that state alone—ends up disposed of improperly in sewers, soil and trash. Multiply that by 50 states and it is easy to see how used motor oil might well be one of the largest sources of pollution affecting groundwater and our nation’s waterways. The implications are startling indeed, as one quart of oil can create a two-acre sized oil slick, and a gallon of oil can contaminate a million gallons of fresh water.

Conventional motor oils are derived from petroleum, whereas synthetic oils are replicas manufactured from chemicals that are really no kinder to the environment than petroleum. As such, conventional and synthetic motor oils are about equally guilty when it comes to how much pollution they create. But Ed Newman, Marketing Manager for AMSOIL Inc., which has been producing and selling synthetics since the 1970s, believes that the synthetics are environmentally superior for the simple reason that they last about three times as long as conventional oils before they have to be drained and replaced.

Additionally, Newman says that synthetics have lower volatility and therefore do not boil off or vaporize as quickly as petroleum motor oils. Synthetics lose from four to 10 percent of their mass in the high heat conditions of internal combustion engines, whereas petroleum-based oils lose up to 20 percent, he says. Economically, however, synthetics are more than three times the cost of petroleum oils, and whether or not they are worth the difference is the subject of frequent, inconclusive debate among auto enthusiasts.

But before deciding for yourself, consult your car’s owner’s manual regarding what the manufacturer recommends for your model. You can void your car’s warranty if the manufacturer requires one type of oil and you put in another. For instance, some Chevrolet Corvettes require synthetic motor oil only.

While synthetics seem to be the lesser of two evils for now, some promising new alternatives derived from vegetable products are coming of age. A pilot project at Purdue University, for example, has produced motor oil from canola crops that outperforms both traditional and synthetic oils with regard to both performance and production price, not to mention greatly lessened environmental impact. Despite the benefits, though, mass production of such bio-based oils would probably not be feasible, as it would require setting aside large amounts of agricultural land that could otherwise be used for food crops. But such oils may have a place as niche players as the worldwide market for petroleum products diversifies due to dwindling reserves and related geo-political tensions.

CONTACTS: AMSOIL,; Purdue Research on Canola-based Motor Oils,