MOTOR oil would seem to be a good candidate for a green makeover, especially because Americans use so much of it, and often dispose of it improperly. According to a survey by the National Petrochemical and Refiners Association, 585 million gallons of engine oil, under a huge number of brand names, were sold for gasoline engines in 2007.

Standard motor oil is not exactly environmentally friendly, especially once it is used. The Department of Health and Human Services says oil can contain such toxic substances as benzene, lead, zinc and cadmium. Consumers are urged to dispose of used oil properly at recycling centers, including local garages.

While an automotive-products company in Stamford, Conn., has not solved the recycling problem, it says it has developed a way to make engine oil a bit greener. And the solution involves cows — thousands of them.

Image Green Earth Technologies has been selling G-Oil since last May.

The company, Green Earth Technologies, has been selling G-Oil since last May. The oil is made from beef tallow and is a byproduct of the slaughterhouse business. According to Dr. Mat Zuckerman, the company president, one cow yields 110 quarts of oil. In the Oklahoma panhandle some 50,000 cattle are processed every day within 150 miles of the company’s plant in Guymon. Does that make G-Oil green and a renewable resource? Dr. Zuckerman said he thought so.