In a large mixing bowl, dissolve yeast in the 1 cup warm water. Let stand for 5 minutes. Stir in 1 1/2 cups of the flour, the 1/3 cup vegetable oil, and salt. Beat with an electric mixer on low speed for 30 seconds, scraping the bowl constantly. Beat for 2 minutes on high speed, scraping the bowl frequently. Using a wooden spoon, stir in as much of the remaining flour as you can.