Preheat the oven to 350°F degrees. Line 3 8” cake pans with parchment rounds, spray with oil and lightly dust with flour. Set aside
In a medium bowl, combine the all-purpose flour, cocoa powder, salt and whisk to combine. Set aside.
In a stand mixer fitted with a paddle attachment, combine butter and sugar and beat on medium speed for 3-5 minutes or until light and fluffy. Add oil and mix to combine.
Add eggs one at a time, mixing until each egg is incorporated before adding the next egg. Add the red food coloring and beat until combined.
With the mixer on medium-low speed, alternate adding the dry ingredients and buttermilk; beginning and ending with the dry ingredients. Be careful to not over mix the batter. Stop the mixer when a few ribbons of flour are visible.
Combine the warm water, baking soda and vinegar in a small bowl. Bubbles will begin to form- add to the batter and mix for 10-20 seconds on medium-low speed.
Evenly distribute the cake batter into each prepared cake pan and bake for 30 minutes. Check cakes by inserting a toothpick in the center. If it comes out clean or with a few crumbs- cakes are done! *Each oven varies and baking times may differ by 5-10 minutes. Check cake for doneness at 28 minutes.
Place on a cooling rack for 10 minutes in the pan before turning the cake pan upside down to release the cake to completely cool.
Prepare the frosting