To Make Crust: In a large bowl, mix together 1 1/2 cups flour, oil, milk, 1 1/2 teaspoons sugar and salt until evenly blended. Pat mixture into a 9 inch pie pan, spreading the dough evenly over the bottom and up sides. Crimp edges of the dough around the perimeter.
To Make Filling: Mix together 3/4 cup sugar, 3 tablespoons flour, cinnamon, nutmeg, lemon juice and corn starch. Sprinkle over apples and toss to coat and heat in sauce pan until tender. Spread evenly in unbaked pie shell.
To Make Topping: Using a pastry cutter, mix together 1/2 cup flour, 1/2 cup brown sugar, 1/4 cup white sugar and butter until evenly distributed and crumbly in texture. May add cinnamon, rolled oats, or chopped pecans if desired. Sprinkle over apples.
Put pie in the oven on a cookie sheet to catch the juices that may spill over. Bake 45 minutes.