Combine sugar, instant potatoes and warm water to form starter; place in plastic container and cover loosely. Place in refrigerator for 3-5 days.
After 3-5 days, remove from refrigerator and feed with sugar, instant potatoes, and water; mix well and let stand out of refrigerator all day. At the end of the day, remove 1 cup to use in making bread and return the rest of the starter to the refrigerator, keeping loosely covered. Repeat feeding every 3-5 days. If not making bread after each feeding, dispose of 1 cup or give or throw away.
Place 1 cup of starter in a large bowl and add sugar, corn oil, salt, warm water and bread flour. Make into a stiff batter. Roll in corn oil and put in large greased bowl or dishpan. Cover lightly with saran wrap; leave on counter overnight to rise.
After rising, punch down and divide into 3 parts. Knead each part on floured surface (12 times) and put into greased loaf pans (glass pans are best). Brush with corn oil. Cover lightly with saran wrap. Let stand and rise 6-12 hours.
After rising again, bake on bottom rack 30-35 minutes at 350º. Remove from oven when golden brown and brush with melted butter; cool.