King County has purchased re-refined motor oil since 1992. This helps the environment by reducing the impacts of refining and also conserves a non-renewable resource. Engine lubricating oil does not "wear out." Producers can re-refine oil to remove contaminants introduced during its use and replace the "additive packages" that confer its specific properties, such as viscosity. Current technologies allow used oil to be re-refined into a high-quality base-stock and several oil companies manufacture products that have been certified by the American Petroleum Institute (API).

Biobased lubricants are derived from plants and other renewable agricultural, marine, and forestry materials and also conserve resources. These can be used in the same systems as petroleum based products. Equipment usually includes a label that identifies that biobased lubricants have been used.

King County’s Renton Maintenance Facility of the Fleet Administration Division (Fleet) has purchased vegetable-based hydraulic oils for use in their equipment, from lawn mowers to dump trucks, since 2001.