Over the years, the norms around what to do with used oil have changed.

Used to be you tossed it down the nearest drain. Then came recycling.

As energy prices soared, using old oil as heating fuel in special-purpose space heaters arrived.

Now, the loop has closed, and used oil can be considered feedstock to provide ... new, clean, fresh oil.

And Universal Lubricants, one of the companies that does that recycling, has signed up a major customer: Enterprise Holdings, which operates the Alamo, Enterprise, and National car-rental brands throughout the United States.

Starting in five states, Universal will collect all the used oil from regular oil changes at those rental-car maintenance garages. It will "re-refine" the oil into its Eco Ultra motor oil, and provide that new oil to Enterprise mechanics for use in those same cars.

According to Universal, just 10 percent of the 1.3 billion gallons of used oil removed each year from U.S. vehicles is re-refined.

The process takes place at a Universal facility in Wichita, Kansas. Water, fuel, and solvents are removed, along particles of metal, asphalt, and other heavy contaminants.

Finally, the resulting purified oil base stock is blended with high-performance additives to produce new Eco Ultra oil. According to Universal, the oil is certified by the American Petroleum Institute.

[Universal Lubricants]

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