If you're a country, having "petroleum exporter" on your business card makes marketing irrelevant and the sales process a formality. Oil's role as the backbone of economies around the globe provides a steady supply of customers ready to buy. We heat homes with it and transform it into textiles and composite materials used to make cars and airplanes. Gasoline, plastics, fertilizer and building supplies come from petroleum, as do polymers used to manufacture medical devices such as prosthetics and heart valves. Petroleum enhances life for its buyers, but it doesn't always bring prosperity to its exporters.