All rolled oats are cooked before being flattened, including traditional, quick oats, and instant. The difference is only how thin and small the pieces are (how close the rollers are). So all types are already gelatinized and can be added directly to the mash. I use Quaker traditional (the kind that takes 5 minutes to cook) because its what I have on hand for oatmeal - I like the texture better than quick or instant. But for beer, texture doesn't matter. I wouldn't use instant only because its probably more expensive.