Mix the poolish the night before and leave covered at room temperature.
Cook the oatmeal and let it cool completely.
In a measuring cup, combine warm water, honey, and yeast. Let sit 15 minutes until foamy.
In the bowl of a stand mixer fitted with a dough hook, add yeast mixture, flour, cooled oatmeal, poolish, oil, and salt.
Mix on speed 1 for 2 minutes until combined. Increase to speed 2 and knead 12 to 15 minutes until smooth and elastic. The dough should pull away from the bowl.
Transfer dough to an oiled bowl. Cover and let rise in a warm place for about 1 hour until doubled.
Turn onto a lightly floured surface. Shape tightly into a loaf and place in a greased loaf pan.
Brush with water and top with oats.
Let proof until the dough fills the pan.
Bake at 350°F for 35 minutes on the center oven rack until golden and internal temperature reaches 190° to 200°F.
Remove from pan and cool completely on a wire rack before slicing.