Oil dropped to the lowest level in more than four months amid speculation a global glut that drove prices into a bear market will be prolonged. Goldman Sachs Group Inc. said the global crude oversupply is running at 2 million barrels a day and storage may be filled by the fall, forcing the market to adjust, analysts including Jeffrey Currie said in the report dated Thursday. U.S. crude supplies remain more than 90 million barrels above the five-year seasonal average, Energy Information Administration data on Wednesday showed.