Combine the oats, boiling water, molasses and butter and cool the mixture to about 105°F.
Stir the yeast into the warm water and let it stand for 8 minutes until foamy.
Combine both mixtures, add 4 cups flour and the salt, and knead for 8 minutes, adding up to 1/2 cup more flour only until the dough clears the bowl.
Cover and let the dough rise for 60 to 75 minutes until doubled.
Divide it between 2 greased 9-by-5-inch loaf pans and rise for 35 minutes until the crowns sit 1 inch above the rims.
Bake at 375°F for 35 to 40 minutes until the loaves sound hollow and reach 195°F inside, then cool completely before slicing.