Eyeing the used lubricant sample from an unhappy customer, Joseph Fotue Sado of Total Cameroon was stunned. The customer had suffered the sudden failure of a diesel engine, and when the engine was torn down for repair, it revealed a hard, black deposit clogging the crankcase and other parts.
It was so thick that we couldnt measure its viscosity, and even at 150 degrees it didnt flow, Fotue recalled. The black mess even resisted dissolving in a solvent. Was this an act of vandalism, the distressed customer demanded to know, or bad faith on the part of the lubricant supplier? How else to explain a liquid oil that became virtually solid in the engine?