Combine yeast and 1/4 cup warm water in a 1-cup liquid measuring cup; let stand 5 minutes.
Cook 1 3/4 cups water and next 3 ingredients in a large saucepan over medium heat until butter melts. Stir in molasses and buttermilk; cool to 105° to 115°. Stir in yeast mixture.
Combine oats mixture and 1 cup whole wheat flour in a large bowl, stirring until smooth. Stir in remaining whole wheat flour and enough bread flour to make a soft dough.
Turn dough out onto a well-floured surface, and knead until smooth and elastic (10 to 15 minutes). Place in a well-greased bowl, turning to grease top.
Cover and let rise in a warm place (85°), free from drafts, 1 hour or until doubled in bulk.
Punch dough down, and divide in half; shape each portion into a loaf. Place into 2 greased 8 1/2- x 4 1/2-inch loafpans.
Cover and let rise in a warm place, free from drafts, 30 minutes or until doubled in bulk.
Bake at 350° for 30 minutes or until golden brown. Remove from pans immediately, and cool on wire racks.
