Recipe for the Devils food says to add oil, coffee, milk however there is no oil listed in ingredients.

sorry, just added in the 1/2 cup vegetable oil!

I think it's something to do with the Devil being in the details, but I haven't worked it out completely yet.

1/2 cup vegetable oil per her blog.

Ut's on her blog. Click on hr profile and the website is listed. It amazes me how many people have food blogs here! http://www.madelinemarieblog.com/madelinemarie-main/2015/10/8/angel-devils-food-cake