In a large bowl, dissolve the sugar in warm water, then sprinkle the yeast over it. Let it sit for about 5 minutes until foamy.
Stir in the oil and salt. Add flour one cup at a time, mixing until the dough comes together.
Turn the dough out onto a floured surface and knead for 8 to 10 minutes until smooth and elastic.
Place the dough in a greased bowl, cover, and let rise in a warm spot until doubled in size, about 1 hour.
Punch down the dough and divide into two loaves. Shape and place into greased loaf pans.
Cover again and let rise until doubled, about 30 minutes.
Bake in a preheated oven at 375°F for 25 to 30 minutes until golden brown and hollow-sounding when tapped.