Engine oil color reveals its age, contamination level, and operating condition. Fresh oil is amber or light brown. Oil darkened to black but still translucent after a few thousand miles is normal.

Engine oil turns black from a combination of combustion byproducts, heat oxidation, and detergent additives suspending carbon particles in the fluid. Black oil is not automatically a sign of a problem ...

Oil sludge treatment and recovery remain critical challenges in environmental remediation and resource recovery, due to the hazardous nature of sludge generated in petroleum refining and related ...

DETROIT -- An inexpensive device that checks the condition of engine oil and warns the driver when it's time for an oil change could help Volkswagen of America Inc. and the Chrysler group avoid future ...