Chocolate Zucchini Cake

1/2 cup oil
1/2 cup butter or margarine
1 3/4 cups sugar
2 eggs
1 tsp vanilla
1/2 cup sour milk (I used regular milk)
2 1/2 cups flour
4 TB cocoa powder
1 tsp baking soda
1/2 tsp cinnamon
1/2 tsp salt
2 cups grated zucchini
1/2 cup chopped nuts (optional)
1/2 cup chocolate chips

In large mixing bowl combine oil, butter, sugar, eggs, and vanilla.  Add sour milk and sifted dry ingredients.  Mix until smooth.  Stir in grated zucchini.  Pour into greased and floured 9 x 13 inch pan.  Sprinkle top with chopped nuts and chocolate chips.  Bake at 350 degrees for 35 to 40 minutes.