In a large bowl (or the bowl of your mixer), dissolve yeast in warm water. Add the sugar, salt, oil and 3 cups of flour. Mix until smooth. Stir in remaining flour until a it starts to form a soft dough ball (1/2 cup at a time). Make sure to turn off your mixer while you add the flour.
Turn your mixer on and mix for about 4 minutes, until the dough starts climbing up the dough hook. If you are mixing by hand, turn the dough onto a floured surface and knead until smooth and elastic, approximately 8-10 minutes. Place in a greased bowl. Cover and let rise in a warm place until doubled, about and hour and a half.
Punch the dough down and turn onto a lightly floured surface; dived dough in half. Shape each half into a loaf. Place the loaves into two greased 9x5 in. loaf pans. Cover and let rise until doubled, approximately 30-45 minutes.
Bake at 375 degrees for 30-35 minutes or until golden brown and the bread sounds hollow when tapped. Remove from pans to wire racks to cool.
Optional: Put a bit of melted butter on the top of your loaf to make it look nicer.