Preheat oven to 350°F (180°C). In large mixing bowl cream butter and sugar together well. Beat in eggs 1 at a time. Mix in cooking oil, sour milk, vanilla and zucchini.
Mix next 6 ingredients together in small bowl. Add to batter. Stir to moisten.
Spread in greased 9 x 13 inch (22 x 33 cm) pan.
Sprinkle with chocolate chips. Bake in oven for about 35 minutes un-til an inserted wooden pick comes out clean.