Pour oil into skillet to the depth of a little less than 1/2 an inch and heat on medium to medium high for about five minutes. In a bowl, melt margarine. In a separate bowl, combine cinnamon and sugar.
Using a plastic bottle cap, cut the center out of each biscuit. Drop dough into hot oil, watching carefully and turning when golden. Once doughnuts are golden on both sides, remove to paper towel lined plate. Repeat until all dough is cooked, including doughnut holes.
Dip both sides of each doughnut into melted margarine, then press both sides into cinnamon sugar mixture. Serve warm.