Coat the inside of the pan with either Crisco (I like to use the butter flavored) or room temperature butter and then sprinkle flour in the pan being sure to cover every inch of the pan with both the Crisco/butter and the flour. Tap out any excess flour and set the pan aside.
In 2 bowls, seperate the eggs, one bowl with the yolks and the other bowl with the egg whites. Try not to get any yolks in with the egg whites. Add in the cream of tartar into the egg whites and beat until they are fluffy and stiff when you pull out the electric mixer from the egg whites.
In a large mixing bowl, cream the butter until light and fluffy with an electric mixer or stand mixer. Add the sugar and beat until fluffy again, approximately 3 minutes. Scrape the sides of the bowl and add in the egg yolks, beat again. Add the lemon juice, lemon zest, buttermilk and lemon oil. If you don't have lemon oil, substitue lemon extract. You will need 4 tsp of extract to compensate for the lemon oil. Mix until combined. In another bowl add the dry ingredients together, flour, salt, baking soda, and whisk or sift until combined. Add into the wet ingredients ⅓ at a time, mixing in between each addition until just barely combined. The batter should be smooth when all of the dry ingredeitns have been added. If it is not, gently mix until no lumps are found.
Add in the egg whites, and gently fold them into the batter. Do not use an electric mixer, you need to do this step by hand with a rubber spatula, going in slow folding motions. Do this until the egg whites are evenly incorperated into the batter.
Bake in a preheated 325°F oven for about 60-70 minutes, until a toothpick when inserted comes out clean. Remove the cake from the oven and let cool for 10 minutes in the pan.
Remove the cake from the pan and let it cool completely on a cooling rack. If the cake doesn't seem to want to come out of the pan, rest in the pan, upside down on a cooling rack and the cake should eventually come out of the pan.