It's three years since the devastating oil spill in the Gulf of Mexico and BP has transformed itself. But it's still struggling to make good profits. The oil giant made $4 billion in the final quarter of 2012. It beat expectations but was still down a fifth from a year ago. It's already agreed to pay a record $4 billion in criminal penalties relating to the 2010 disaster. But faces further fines next month from the Clean Water Act.