Combine warm water and sugar in a large bowl. Sprinkle yeast over the top and let it sit for 10 minutes until frothy.
Add oil and salt, then stir in flour one cup at a time until dough starts pulling away from the bowl.
Transfer to a floured surface and knead until smooth and elastic, about 6 to 8 minutes.
Place the dough in a lightly oiled bowl, cover, and let it rise for 1 hour or until doubled in size.
Punch down the dough, divide into two portions, and shape into loaves. Place in greased pans and let rise 30 minutes.
Bake at 350°F for 25–30 minutes until golden brown and hollow sounding.
Brush tops with butter and cool before slicing.