Back in the 70's Dad bought an American diesel car (can't remember the make) because diesel was cheaper than gas. He got a bad batch of diesel. After the second major $$$$$$$$$$$ repair bill, he traded it in for a gas car, big loss on the trade.
IIRC the problem was that some bacteria (?) in the fuel had attacked the softer parts of the engine (rubber?) and was eating it away. There was no way of removing all the bacteria and so the second repair.