Oil in the internal combustion engine captures the contaminant by-products of combustion including carbon, soot, and metals from engine wear. When these build up in oil over time, they reduce its effectiveness. Oil also contains performance-enhancing chemical additives, which make up as much as 15 percent of its total volume. These additives become depleted with wear so the processes they prevent, like corrosion or the sludge-forming mixing of oil and water, become problematic when oil has been used too long. This is why changing the oil in you car’s engine is part of a good preventive maintenance program. The Postal Service used over 220,000 gallons of motor oil in FY 2011, most of which was re-refined motor oil.
Why use re-refined motor oil? The physical property of oil doesn’t degrade. Re-refining used motor oil relies on a practice of vacuum distillation to remove contaminants such as fuel, water, or dirt from used oil to produce new “base oil.” The base oil is blended with a fresh cocktail of additives like dispersants, detergents, and anti-foaming chemicals to restore the oil to its original effectiveness.
It takes only about one-third the amount of energy to recover re-refined base stock as it does to produce the same amount of base stock from crude oil. Using less energy means producing fewer carbon emissions, and the same oil can be re-refined over and over again.
It takes about a gallon (3.8 liters) of used oil to make 2.5 quarts (2.4 liters) of re-refined motor oil, and the base stock can also be used to produce other lubricants like automatic transmission fluid or hydraulic fluid. That’s a lot more efficient than producing “virgin” motor oil; it takes an entire barrel of crude oil (42 gallons/159 liters) to produce the same amount. The math is easy, it takes 42 gallons to make 1 gallon of virgin motor oil but only 1½ gallon of used oil to create 1 gallon of re-refined oil. That makes it 28 times more efficient than buying virgin motor oil.
The Postal Service is committed to a more sustainable use of petroleum products. You can help by making sure you buy re-refined oil.
