Combine the yeast, sugar, and warm milk in the bowl of a standing electric mixer. Stir with a wooden spoon and let stand for 10 to 15 minutes, until the surface appears foamy.
Stir in the melted butter and 3 of the eggs and stir until thoroughly combined. Fit the mixer with the paddle attachment and place the mixing bowl on the mixer.
Sift the flour and salt into a medium mixing bowl.
With the mixer running on low speed, carefully add 31/2 cups of the flour, one cup at a time, until a soft, sticky dough is formed. Be careful to stay clear of the rotating paddle! Add the remaining flour in 1/4-cup increments. You may not need all of the flour. To know whether you have added enough flour, test the dough by turning off the mixer and touching the dough with your finger. It should remain slightly sticky and not at all dry. If itís getting dry and very stiff, do not add any more flour.
Increase the mixer speed to medium-low and allow the paddle to knead the dough until the dough is very smooth and elastic, about 5 minutes.
Grease a large mixing bowl with the oil and add the dough to the bowl. Turn the dough so that it is coated with oil. Then cover the dough with plastic wrap or a clean, damp kitchen towel, and let it stand in a warm, draft-free place to rise until doubled in size, 1 to 11/2 hours.
Punch the dough down with your fist before turning it out onto a clean work surface, and then divide it into 3 equal portions. Using your palms, start in the center and work outward, rolling each portion of dough gently against the work surface with even pressure to form a rope about 20 inches long. Repeat with the rest of the dough.
Press the 3 ropes together at one end to seal. Lay the 3 ropes next to one another, with the sealed end farthest away from you. Begin braiding
the loaf by crossing one of the outer ropes over the center rope. Continue to braid by crossing alternating outer ropes, one at a time, over the center rope. When the ropes are completely braided, press the ends of the 3 ropes together and transfer the loaf to a parchment-lined baking sheet. Tuck the pinched portions of the ends under slightly so that they are not visible. Cover with plastic wrap or a clean, damp kitchen towel and set aside in a warm place until loaf has doubled in size, about 30 minutes.
Position rack in bottom third of oven and preheat the oven to 375?F.
Place the remaining egg in a small mixing bowl and beat lightly with a fork. Using a pastry brush, coat the entire top and sides of the loaf with the eggwash. Bake for 10 minutes, then reduce the heat to 350?F. Continue to bake for an additional 15 to 20 minutes, until the loaf is golden brown and the bread sounds hollow when tapped on the top. Using oven mitts or pot holders, remove the baking sheet from the oven. Let cool before slicing.
Yield: One large (16 - 18-inch) loaf