Formerly Butler and Curtis Oil Inc in Mason City. Consolidated Energy Co. is committed to excellent customer service in the North Iowa Area. We do Sales and Service of Bulk Gas, Cylinders and Motor Fuel. Amoco Mobil Shell. We serve residential, agricultural and commercial customers with gasoline, propane, Amoco premier diesel and No.2 diesel. We specialize in bulk and transport deliveries. Give us a call today to discuss your fuel needs.