Heat the oven to 200 F to keep early batches of pancakes warm, if desired.
Combine the flour, cornmeal, baking powder, soda, salt, and sugar; set aside.
In a bowl, whisk together the oil, eggs, buttermilk, and 3/4 cup milk.
Combine the dry mixture with the milk mixture, stirring just until blended. Add a little more milk if too thick. Fold the blueberries into the batter.
Grease a griddle or skillet with oil and set over medium heat.
Measure about 1/4 cup of batter for each pancake and drop on the hot griddle.
When the bubbles are breaking all over the surface of the pancakes and the edges look dry, flip to brown the other side.
If desired keep the finished pancakes warm on a plate or pan in a preheated 200 F oven (or warming drawer) while you make subsequent batches.