In a large mixing bowl combine: the flour, sugar, baking powder, baking soda, and salt. Mix well.
Melt the butter in the microwave and allow a few minutes to cool.
Measure out the milk into a measuring cup with space to add the oil Mix well to combine. Once the butter has cooled a bit, add it as well.
Make a well in the center of the dried ingredients and pour in the wet ingredients.
Mix it all together until it is just combined and there is no dry flour. Don't worry about it being lumpy, the lumps will cook out. You don't want to overmix the batter or your waffles will be tough.
Allow the batter to rest for 10 minutes. The batter will thicken some as the flour hydrates.
Once the waffle maker is hot. Brush butter on both top and bottom of the waffle maker then add your batter. Cook until waffle can be easily removed without sticking and it appears completely set. Repeat this until you have cooked all the waffles.
When the waffles are cool enough to handle, cut them into triangles.