Gradually, volatility gained favor over the Baumé test, though both would continue to be used in combination to specify a gasoline. As late as June 1917, Standard Oil (the largest refiner of crude oil in the United States at the time) stated that the most important property of a gasoline was its volatility. It is estimated that the rating equivalent of these straight-run gasolines varied from 40 to 60 octane and that the "High-Test", sometimes referred to as "fighting grade", probably averaged 50 to 65 octane.