Preheat your oven to 325°F, then liberally spray 2 (8-inch or 9-inch) round cake pans with non-stick baking spray.
In a mixing bowl, sift together the all-purpose flour, baking powder, salt, and baking soda, then set aside. In a separate bowl, whisk together the sour cream, whole milk, lemon zest, lemon juice, and vanilla extract. Set this mixture aside, as well.
In your mixer bowl, use the paddle attachment to stir together the oil, butter and sugar on low speed. Once combined, increase the speed to high and beat the mixture for 4-5 minutes.
Once the mixture is white and slightly fluffy, decrease the speed to low and begin adding the eggs, one at a time. Mix well after each addition and scrape down the sides as needed.
After all of the eggs have been added, increase the speed to medium-high and beat until the mixture is thick and pale yellow in appearance.
With the mixer on the lowest speed, add flour mix and the sour cream mix to batter in stages. Begin with 1/3 of the dry ingredients, followed by 1/2 of the wet ingredients. Scrape down the bowl after the wet ingredients have been incorporated. Continue this mixing in process: 1/3 of the dry, followed by remaining wet ingredients, and lastly the remaining dry ingredients. Scrape down the sides of the bowl and the paddle and mix, on low speed just until the last of the dry mixture is combined.
Finally, using a large spatula, gently fold the flour-coated blueberries into the cake batter.
Divide the batter evenly between your prepared cake pans and bake for 30-35 minutes or until a toothpick inserted into the center of the cake comes out with minimal crumbs attached. The sides of the cake will pull away from the pan, but the center will be springy and bounce back when pressed lightly. Remove pans from the oven and allow them to rest in pans for 5 minutes. Invert cakes from pans onto cooling racks, then allow them to cool completely.