Preheat oven to 350 degrees. Grease and flour three 9-inch round cake pans (spring-form is best).
In a large bowl, cream together butter, oil and sugar until light and fluffy.
Mix in the egg yolks, vanilla, and coconut until combined.
In a separate bowl, mix flour, baking soda, and baking powder, set aside.
In another bowl, beat egg whites until stiff, set aside.
Alternate adding in your buttermilk and flour mixture until combined.
Gently fold in your egg whites.
Pour into prepared baking pans and bake for 20-25 minutes until tops are golden or until toothpick comes out clean.
Let rest for about 10 minutes until you remove from pans, then place on wire racks to cool completely.