Cream togther margarine, sugars, eggs, vanilla and oil. Sift dry ingredients together. Gradually add to creamed mixture; mix well. Chill dough at least two hrs., but preferably overnight. Roll into 3 cm balls and place on ungreased baking sheets, 5 cm apart. Flatten with glass dipped in be frosted with white icing and decorated with sugar crystals. Note: Providing the dough has been thoroughly chilled, these cookies keep their shape extremely well. ----