In large bowl, mix flour, oats, sugar and margarine. Reserve 1/2 cup of the oat mixture. Press remainder oat mixture on bottom of 9x13" baking pan. Bake 10 minutes.
Pour sweetened condensed milk evenly over crust. Sprinkle with nuts and chocolate chips. Top with remaining oat mixture; press down firmly. Bake 25-30 minutes or until lightly browned.
Cut into bars.