Bit before my time (if there ever was such

)
But eons ago, they used to do Redex 'clean your engine out' type events.
A slippery salesman-type would organise a mechanic to drain you engine oil out, replace it with neat Redex(!), rev the con rod nuts out of the engine, and declare it clean. Worked well enough, but they had some spectacular blow-ups. They don't it anymore