Preheat oven to 400 degrees F. Grease muffin cups or line with muffin liners. Combine 1 1/2 cups flour, 3/4 cup sugar, salt and baking powder. Place vegetable oil into a 1 cup measuring cup; add the egg and enough milk to fill the cup. Mix this with flour mixture. Fold in blueberries. Fill muffin cups right to the top.
To Make Crumb Topping: Mix together 1/2 cup brown sugar, 1/3 cup flour, 1/4 cup butter, and 1 1/2 teaspoons cinnamon. Mix with fork, and sprinkle over muffins before baking.
Bake for 20 to 25 minutes in the preheated oven or until done.