A big fuel mixup has left roughly 500 Calgary drivers having to get their vehicles fixed.

It happened at Co-op's Macleod Trail Centre Gas Bar in south Calgary.

Customers there thought they were pumping gasoline on Boxing Day, but were actually putting diesel into their tanks.

Karen Allan, who speaks for the Calgary Co-op, says it was a mistake with a delivery.

"We had a customer who had had some difficulty with their vehicle," said Allan.

"They took it into the repair shop, who discovered the problem right away. They phoned us immediately, and we immediately shut down our pumps, started to investigate what the issue might be and then came to that conclusion."

Allan says Co-op has already spoken with most of the drivers involved and will cover any repair costs and car rentals.

Mechanic's advice

One Calgary mechanic says any long-term damage to a vehicle depends on how much diesel is in the gas tank and how long the diesel has been in the tank.

"I would probably siphon it out and then pump the rest of the tank out with a fuel pump. So, it could cost you $300 to $400 to get that done," said Alvin Klassen of Courtney Automotive in downtown Calgary.

He says once the tank has been refilled with gasoline, the problem should work itself out over time.