Mix buttermilk and oats in a large bowl; let stand for 15 minutes.
On waxed paper, combine whole-wheat flour, all-purpose flour, wheat germ, baking powder, baking soda, salt and cinnamon. Stir eggs, sugar, oil and vanilla into the buttermilk mixture. Add the dry ingredients to the wet ingredients; mix with a rubber spatula just until moistened.
Coat waffle iron with cooking spray and preheat. Spoon in batter to cover three-fourths of the cooking surface. Cook until waffles are crisp and golden brown, 4 to 5 minutes. Repeat with remaining batter. Batter can also be used for pancakes. 6 servings.