The US uses 710 million gallons per day. In fact, every 22 minutes, the US uses up what spilled in the Exxon Valdez spill. Every day 31.5 billion gallons of oil are at sea being transported. But not all spills come from tankers. Some comes from storage tanks, pipelines, oil wells, tankers and vessels cleaning out tanks.
Oil generally floats because it is lighter than water.
A good experiment to do here is to add vegetable oil, which acts like crude oil, to food-colored water in a large, clear plastic soda bottle with a cap. Shake it and watch how the oil always settles on top. Sheens are often seen as rainbow-like or silvery in puddles in parking lots. It is very rare for oil to sink. It needs to adhere to heavier particles such as sand, algae, or silt to sink.