In a large mixing bowl, dissolve the yeast in 1 cup of the warm water. Let stand 5 mins. until yeast foams. Stir in the salt, oil, honey, remaining water, and buttermilk. Mix in the rye flour, wheat germ, and whole wheat flour; beat well. Add bread flour, 1 cup at a time, beating well until stiff dough forms. Turn dough out onto lightly floured board and knead until smooth and elastic, about 10 mins., adding additional bread flour as needed. Wash bowl, grease it, and add dough to bowl. Turn over to grease top of dough. Cover and let rise in a warm place until doubled. Grease four 81/2" bread pans. punch dough down. Divide into 4 parts. Shape each into a loaf and place in pans. Cover loosely. Let rise until about doubled. Bake in preheated 375 degree oven for approx. 40 mins.