Drivers think more about the gasoline or petrol they pay for at the pump than they do about the motor oil that has to be changed every few months.

But energy companies and environmentalists are focusing on ways to reduce the waste generated by this ubiquitous petroleum product. They’re even researching how the right formulas might significantly boost fuel efficiency.

Tens of millions of barrels of lubricant cycle through vehicle engines around the world each year—U.S. drivers alone produce about 1.3 billion gallons of dirty used motor oil annually. Too much of it—the U.S. Environmental Protection Agency (EPA) estimates 200 million gallons (757,082 liters)—is dumped illegally each year. Some is “recycled,” but with dubious environmental benefit; it typically ends up burned as