Watching a lady reverse a very large van between my car and the other petrol pump, I was distracted enough to pick up the petrol instead of diesel filler. I only put in two litres of petrol before realising what I was doing. I stopped and after hesitating, decided to carry on and fill up with diesel. I put in 40 litres of diesel. Will I get away with it or should I have the tank drained? The car seems to be running as normal.