Combine the flour, baking soda, baking powder, and salt in a medium bowl; set aside.
With your mixer, combine the oil, butter, and sugars on medium speed.
Add the eggs and mix on medium speed.
Add in the sour cream and bananas and mix on medium low speed until combined.
Gradually add the dry ingredients and mix on low speed until just combined.
Add any add-ins you may be including and fold them in until just combined. Be sure not to overmix the batter.
Pour the batter into the prepared loaf pan. Bake for 55 to 65 minutes or until a toothpick inserted into the center comes out clean. If it isn’t quite finished but the top is browning too quickly, loosely tent the pan with foil.
Cool on a wire rack for about 15 to 20 minutes, then remove it from the pan and place on the wire rack to finish cooling.