Grease muffin cups or line with paper muffin liners.
In a small bowl, combine milk and oats and let soak for 15 minutes. In a separate bowl, beat together egg and oil then stir in oatmeal mixture. In a third bowl, sift together flour, sugar, baking powder and salt. Stir flour mixture into wet ingredients, just until combined.
Spoon batter into prepared muffin cups until cups are 2/3 full. Bake in preheated oven for 20 to 25 minutes, until a toothpick inserted into the center of a muffin comes out clean.