Look at it like this -
5 weeks ago here in KC, I could fill up at 2.92/gal. Some places I saw get as low as 2.89/gal. Fast forward to today in KC where gas is now 3.69/gal, an 80 cent raise in just over a month. Say in KC alone there are 250,000 people that fill up a 12 gallon tank today. Compared to last month, oil companies are making $2,400,000 more in one day in one city. Spread that over the entirety of the nation, and you're talking hundreds of millions, if not billions more that they will make today as compared to last month.
All due to "maintenance".