"Green" Motor Oil—From Cow Fat?

Eco-friendly but seemingly too-good-to-be-true car products are all the rage right now–check out the 30,000-mile biodegradable oil filter, which claims that dirty oil run through it will come out "as clean or cleaner than new engine oil."  ***The miracle oil is made from cow tallow–that same slaughterhouse byproduct used in shortbread and fabric softener. Considering the role of animal agriculture in despoiling the earth, it’s hard to argue that such an oil would be truly "green." If you think ethanol production is an ecological disaster, just imagine the quadrupling or quintuppling of the carbon footprint you’ll get if you have to cycle all that corn through a voracious, land-hogging, farting cow herd before turning it into an automotive consumable.