In large bowl, combine 3 cups flour, oats, sugar, yeast and salt; mix well. In small saucepan, heat water, milk and margarine until very warm (120ºF to 130ºF). Add to flour mixture. Blend on low speed of electric mixer until dry ingredients are moistened. Increase to medium speed; beat 3 minutes. By hand, gradually stir in enough remaining flour to make a stiff dough. Turn dough out onto lightly floured surface. Knead 5 to 8 minutes or until smooth and elastic. Shape dough into ball; place in greased bowl, turning once. Cover; let rise in warm place 30 minutes or until doubled in size. Punch down dough. Cover; let rest 10 minutes.
Divide dough in half; shape to form loaves. Place in two greased 8 x 4 or 9 x 5-inch loaf pans. Cover; let rise in warm place 15 minutes or until nearly doubled in size. Heat oven to 375º. Bake 45 to 50 minutes or until dark golden brown. Remove from pans to wire rack. Cool completely before slicing. If desired, brush tops of loaves lightly with melted margarine or butter and sprinkle with additional oats after placing in pans.