Preheat oven to 350 degrees F (175 degrees C). Grease and flour two 8x4 inch loaf pans.
In a large bowl, combine flour, baking soda, baking powder, cinnamon, nutmeg and salt. In another bowl, beat together oil, sugar and vanilla. Stir in zucchini. Add dry ingredients to wet ingredients; mix just until blended. Fold in walnuts.
Divide batter into prepared pans. Bake for 40 to 50 minutes or until a toothpick inserted into the center of the loaf comes out clean.
Cool in pan for 10 minutes before turning out onto a wire rack to cool completely.