Put water in a large bowl. Add yeast; stir to dissolve. Add brown sugar, gluten and whole wheat flour. Beat well, about 200 strokes. Let yeast develop for about 10 minutes. Add oil and salt; mix thoroughly. Add 2 cups of the bread flour; beat well. Work in enough of the remaining bread flour until a soft dough is formed.
Turn out onto a lightly floured surface and knead 6 to 8 minutes, or until dough is smooth and elastic. Place in large oiled bowl and turn to coat lightly. Cover bowl with a clean damp towel or plastic wrap. Let rise in a warm, draft-free place about one hour, or until doubled in bulk.
Punch down dough. Divide dough into two equal pieces and form each piece into a smooth loaf. Place in greased 9x5-inch loaf pans. Cover and let rise about 45 minutes, or until nearly doubled.
While dough is rising, preheat oven to 400°F. Bake loaves about 35 minutes, or until top is golden brown. Bread is done when it slides easily from the pan and sounds hollow when tapped on the bottom. Let cool on wire racks.