Mix first 6 ingredients in a large bowl.
Stir in buttermilk, oil and egg yolks.
Using an electric mixer, beat egg whites until medium-firm peaks form. Gently fold egg whites into batter.
Heat a heavy large skillet over medium-high heat; lightly brush skillet with melted butter. Drop batter by ¼ cupfuls into skillet; spread to 4 inch rounds. Sprinkle 2 tablespoons blueberries over each round. Cook until tops are covered with small bubbles and bottom are golden, about 2 minutes. Turn and cook until second sides are golden, about 1 minute.
Repeat with remaining batter and blueberries, brushing skillet with melted butter for each batch.