Yes, the oil industry is engaged in price fixing. Three businessmen were charged with price fixing oil in 2007. Even though this was nine years ago, it still might mean that this could happen today. Recently, the price of gas has been rising while the price of an oil barrel is falling. All of this points to buyers and sellers negotiating to fix oil prices in the industry.
I don't know that the companies call each other up and discuss what the price should be today, but they must keep an eye on each other. The prices are too similar. In theory, a gasoline company that bought a lot of crude oil at one price per barrel should be selling at a lower price than another company that had to purchase its oil at a higher price. But I never see that, never for instance see Exxon selling five cents a gallon lower than BP this week, because they had a particularly favorable crude contract.
Yes, the oil industry is engaged in price fixing as a standard industry practice. The Organization of the Petroleum Exporting Countries, or OPEC, constantly adjusts production in order to drive oil prices world wide in a manner that benefits its member countries. Individual oil companies also work to fix prices in both the U.S. and abroad.
The oil industry is run by a small select group of leaders that have the power to set prices and manipulate the supply. It was well known the U.S was vulnerable to the Middle Eastern countries during a period of high oil prices and we have developed other strategies to be more independent of our fuel needs.
It's not a secret that the organization of petroleum-exporting countries (OPEC) is a price-setting cartel. According to Wikipedia's page, OPEC's stated mission is "to coordinate and unify the petroleum policies of its member countries and ensure the stabilization of oil markets, in order to secure an efficient, economic and regular supply of petroleum to consumers, a steady income to producers, and a fair return on capital for those investing in the petroleum industry." OPEC holds and estimated 73% of global oil reserves. So I would say, yes, there is no doubt that price fixing is a feature of the global oil market.