What if I told you about a motor oil that is eco-friendly, biodegradable and not made from fossil sources? What if I told you it was so good that top racing teams use it?

You’d want to buy it for your car, right? Well now you can, everywhere from Home Depot to True Value hardware, because on March 10 it was approved for widespread sale by the American Petroleum Institute (API), whose “Donut” symbol will be on every bottle.

OK, now here’s the gross part. It’s made from animal fat. Beef tallow, actually, a waste product from slaughterhouses. “Save the Earth!” the company says. “It takes three barrels of crude oil to make one barrel of motor oil, but only one barrel of animal fat to make one barrel of G-Oil.”

That’s what it’s called, G-Oil. The Connecticut-based company just signed a two-year contract to make its Race 1 “the official motor oil of The American Le Mans Series and the International Motor Sports Association (IMSA).”

“Think about it,” CEO Jeff Marshall told MNN. “These Le Mans racers go around the tracks for 24 hours, covering hundreds of miles at incredible RPMs. The oils they use have to be far superior to regular motor oil. But the Le Mans series also want to be a leader in green racing — they want the whole series to be green.”

G-Oil was, in fact, being used in racing even before the API certification. “We also want to get into go-karts,” said Marshall, “because we make a two-cycle oil that doesn’t smoke and can be used to reduce emissions.”

Could we really produce a significant amount of our motor fuels (and even gasoline and diesel) from animal fat? Warning: more gross stuff ahead: One cow yields 110 quarts of oil, and G-Oil’s Mat Zuckerman says that 50,000 of them are “processed” daily within 150 miles of the company’s plant in Oklahoma. “We could make all the motor oil the country needs from 50,000 cows a day,” Zuckerman told me. “It doesn’t have to be made from petroleum.”

Vegetarians (like me) are squeamish about this kind of thing, but all those poor cows are going to die anyway. And G-Oil is not the only company looking at making motor fuels and oils from beef tallow. ConocoPhillips and Tyson Foods announced a strategic alliance in 2007 to make diesel fuel from “beef, pork and poultry by-product fat.”

I’d add that the process uses a proprietary thermal depolymerization production technology, but that’s probably more than you want to know.