Preheat oven to 350 F. Grease 3 8″ cake pans with butter. Line with parchment paper. Grease parchment paper with butter.
In a medium bowl, whisk to combine the flour, baking powder, and salt. Set aside.
In a standing mixer fitted with the paddle attachment or in a large bowl using a hand held mixer cream the butter, lime zest, and sugar for 2 minutes
Add the oil and beat for another minute.
With the mixer on medium speed, add the eggs one at a time til incorporated.
Add the vanilla extract followed by the sour cream. Beat til just incorporated.
Add in half the dry ingredients. Mix on low speed til just incorporated. Beat in the milk followed by the other half of the dry ingredients.
Pour cake batter evenly among the three pans. Bake for 24-29 minutes or until a tooth pick comes out clean when inserted into the middle of the cake. Place cake pans on a wire rack and allow to cool completely before frosting.