Engine oil turns black from a combination of combustion byproducts, heat oxidation, and detergent additives suspending carbon ...

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.

This may sound like something out of the original "CSI: Crime Scene Investigation" TV series, but you can tell a lot about engine health by pulling out the dipstick, reading the oil level, and ...