Dissolve yeast in 1/2 cup warm water.
In a large bowl, combine the 1-1/2 cups boiling water, the rolled oats, molasses , shortening and salt, cool to lukewarm.
Stir in 2 cups of the flour. Add eggs and beat well.
Add remaining flour, 2 cups at a time, mixing vigorously after each addition, to make a moderately stiff dough. Beat vigorously till smooth (about 10 minutes).
Grease top lightly. Cover tightly. Place in refrigerator at least 2 hours or overnight.
Turn out on well floured surface: shape in 2 loaves. Place in greased loaf pans.
Cover; let rise in warm place till double in size (about 2 hours).
Bake in moderate oven (375 °F) for about 40 minutes.
If crust browns too quickly, cover with foil for last half of baking time.
Yield: 2 loaves.