Mix the oil and sugar together well, then add the eggs. Sift all the dry ingredients together and add to the egg mixture alternately with the sour cream. Add the vanilla and fold the blueberries in. Pour the batter into a well greased 9x13 inch pan.
For the topping:
Combine ingredients and sprinkle on top of the batter. Bake at 350 degrees for about 40 minutes. Do not over bake! This is very good when served warm.