Several car owners were left with expensive repair bills after a Massachusetts gas station’s premium fuel tank was mistakenly filled with diesel last month. The incident occurred on December 21 when a tanker driver wrong-slotted his hose at the Speedway gas station in South Boston as he tried to top up the stations’s underground reservoir.

When drivers pulled the trigger on the premium pump’s handle their cars were filled with the stinky stuff, though many didn’t realize until later when their cars began to run badly. And in at least one case, stopped running altogether.

One driver told WCB-TV that the mixup had cost him $1,400 which was the invoice a garage presented him with in return for draining the diesel from his car, flushing the fuel lines, and replacing the fuel filters and spark plugs. But the expense doesn’t end there. The man was told that the mistake also ruined his catalytic converter, which could cost $2,000 to replace.

Another driver’s Mercedes SUV started making a rattling noise when she turned it on, then threw in the towel. It’s currently at a Mercedes dealer potentially needing major engine surgery. The owner only twigged the cause of the problem when she read a Facebook post from yet another driver who had been affected and had the mis-fuelling mixup confirmed by a Speedway employee. It’s not known how many drivers were affected in the incident.

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Thousands of drivers accidentally put the wrong fuel into their car each year, but provided they realize their error and call for recovery before starting the car, they can get away with flushing out the fuel tank and lines. That’s still inconvenient, but it won’t cost a fortune. Things get more serious, and potentially far more expensive, if you drive away before realizing, as these owners have discovered.

This isn’t the first time we’ve reported on this kind of mistake by a tanker driver. The same thing happened in Hamilton, Ontario, a couple of years ago. The good news in this Boston case is that Speedway has shut the pumps off as soon as it was alerted to the problem and has promised to reimburse the repairs costs – and presumably the fuel costs – of anyone affected by the mistake. If you believe you were affected you can call Speedway on 1-800-255-0711.