Preheat oven to 425°F (220°C).

Sift together flour, baking powder, salt, and sugar in a bowl.

Stir in rolled oats.

In a separate bowl, combine vegetable oil, beaten egg, and milk.

Add the wet ingredients to the dry ingredients.

Stir until just moistened, being careful not to overmix.

Grease a 12-cup muffin tin.

Fill each muffin cup 2/3 full.

Bake in the preheated oven for about 15 minutes, or until a toothpick inserted into the center comes out clean.

Let cool in the muffin tin for a few minutes before transferring to a wire rack to cool completely.