Your engine oil is as essential to your car as your blood is to your body. Without it, your motor won’t run. And just like a doctor can tell a lot about your health by testing your blood, you can ...

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 ...