Warm the water and whole milk to about 110°F (43°C).

In a bowl, combine warmed water, warmed milk, and yeast; let sit until foamy.

In a large mixing bowl, combine 2 cups whole wheat flour, 1 and 1/3 cups whole wheat flour, salt, honey, butter, lemon juice, and oats.

Add the yeast mixture to the dry ingredients and mix until a dough forms.

Knead the dough on a floured surface until smooth, about 10 minutes.

Place the dough in a greased bowl, cover, and let rise until doubled in size, about 1 to 2 hours.

Punch down the dough and shape it into a loaf.

Place the loaf into a greased loaf pan, cover, and let rise again until doubled, about 30 minutes.

Preheat the oven to 350°F (175°C).

Bake for 38 minutes or until golden brown and sounds hollow when tapped.

Let cool before slicing.