Preheat oven to 350°F. In a large bowl, stir together dry ingredients. Add oil and eggs; mix thoroughly.
In a smaller bowl, mash bananas with a potato masher or fork. Add bananas and oatmeal to batter.
Spray a loaf pan with cooking spray. Pour batter into pan and bake until top of loaf is firm to touch, 45 to 55 minutes. Remove from oven and allow to cool in pan for 5 minutes. Flip out and cool on a wire rack for another 10 minutes.