Lubricating oils originate from either the engine’s crankcase or through mechanical pumps. Oil-sensitive components like valves, bearings, and gears can be cut by a film of metal.
In addition, as metals build up on the surfaces that they contact, their inherent magnetic properties decrease resistance to heat transfer which increases wear rates. Items tend to wear out when excessive buildup occurs or due to faster moving contact points than designed for.
Originally published on quora @sequoia-global