Preheat oven to 350 degrees F.
In a medium mixing bowl, add the ground oatmeal or breadcrumbs.
Add the milk and allow the oats to soak for a couple of minutes.
Add the ground beef, egg, onion, salt and pepper and mix thoroughly.
Add to a loaf pan.
In a small bowl, mix sugar, ketchup and ground mustard and mix thoroughly.
Spread evenly over top of meat mixture.
Bake at 350 for 45 minutes.