To prepare a whole wheat olive oil and citrus loaf cake recipe, first you'll need to prepare the ingredients. First, preheat the oven to 350 degrees F (180 degrees C). Then, mix the flour, baking powder, sugar, and salt together in the large mixing bowl. Next, add the oil to the dry ingredients and stir to combine. Add the eggs and vanilla and mix until combined. Pour the batter into the greased loaf pan and bake for 35 to 40 minutes. Let the cake cool before removing it from the pan.