In a large bowl, combine the flour, the 2 cups wheat flour, salt, sugar and yeast. Stir to combine.
Add cold water and whisk until the dough comes together.
Pour the oil on top and rub the top with the oil, smoothing out the top.
Cover with plastic wrap sprayed with non stick spray and a kitchen towel and leave to rise until doubled in size, approximately 6 hours.
Spray a 9x5 loaf pan with non stick spray.
Fold the batter over a few times by pulling the dough from underneath over the top. Place seam side down in the prepared loaf pan.
Sprinkle the top with the remaining whole wheat flour. Make 3 slits on the top. Cover loosely with plastic wrap sprayed with non stick spray. Leave to rise again until it rises 1/4" above the rim of the pan, about 30-45 minutes.
Preheat oven to 375 F.
Bake for 50 - 60 minutes, until loaf sounds hollow when tapped.
Notes
You can also do the first rise overnight in the refrigerator.