Preheat oven to 425. In a mixing bowl, combine flour, salt, milk, and oil. Add one teaspoon cold water at a time until dough mixture begins to clump together. If the dough doesn't clump together when pinched, add another teaspoon of water. On a lightly floured surface, roll dough to a circle 1 1/2" larger than inverted pie pan. Pick dough up and gently ease into pie pan, being careful not to stretch dough. Trim half inch beyond edge of pie pan, fold under to make double thickness around rim. Flute edges as desired. Prick bottom and sides of crust with a fork. Bake for 15 minutes. Meanwhile to prepare filling, combine pumpkin pie mix, pumpkin pie spice, milk, and egg whites. Mix well. Pour mixture into baked crust. Reduce heat to 350 and bake for one hour, or until toothpick inserted into center comes out clean or until center is completely set.