Originally posted by 235 Fat Fenders:
Why would you not use it in the engine?
It's probably fine in modern engines and heavy duty (truck) use, but it's not good in motorcycles with "wet" clutches where the clutch runs in crankcase oil. It may not be the best idea in old engines either, although I don't know the reason. Perhaps the old type seals aren't good at dealing with it or it may cause sludging in high mile or non-pressure lubricated engines.
Some one else may be able to say exactly why.
