Preheat oven to 400°F (200°C). Grease or line 8 muffin cups.
In a large bowl, whisk together flour, sugar, baking powder, and salt.
In a small measuring cup, combine vegetable oil, egg, and enough milk to reach 1 cup; stir to combine.
Pour wet mixture into dry ingredients and mix until just combined. Gently fold in blueberries.
In a small bowl, mix together sugar, flour, butter, and cinnamon with a fork until crumbly.
Spoon batter into prepared muffin cups, filling to the top. Sprinkle with crumb topping.
Bake for 20-25 minutes, until a toothpick inserted in the center comes out clean.
Let cool before serving.