Preheat oven to 350 degrees Fahrenheit; grease a 9x5 inch loaf pan.

Whisk flour, baking soda, salt, and cinnamon in a medium bowl.

Beat oil, sugar, and eggs in a large bowl until smooth.

Stir dry ingredients into wet until just combined.

Fold in diced mango and walnuts.

Pour into prepared pan; bake 55 to 65 minutes, or until a toothpick inserted in center comes out clean.

Cool in pan 15 minutes; transfer to a wire rack.