In a large bowl, sift together all-purpose flour, salt and baking soda. Add whole wheat flour and sugar; stir to combine. In a separate bowl, mix together buttermilk, milk and oil.
Add milk mixture to flour mixture; mix just until combined. Divide dough in half and form into two round, flat loaves. Place loaves on a lightly greased baking sheet.
Bake in preheated oven for 15 minutes. Reduce heat to 375 degrees F (190 degrees C) and bake for an additional 25 to 30 minutes, until golden brown.
