I mix some of the oats with a bit of flax seed and some bran flakes, maybe add some chick starter crumbles or some red pepper flakes. On occasion I even add a bit of DE. It depends on what I am feeding it for and to whom as to what I add but the chickens all love it and like the variety of treats I add to it.
I have even put in some bird seed but I always wet it and mix well. They go bonkers over it where as they never will eat Cheerios like other people say their chickens love them.
Oatmeal is a standard on our shelves in the coop area, as is DE and red pepper flakes and the flax seed and bird seed.
I used to treat my birds with Quaker Oats, but Now I do the same as picklespickles, I get a bag now and then at my local feed store. I give it to them dry but have wet it and given it to them that way too. If you have vegie scraps you can give them to your birds also. I don't give them potatoe peals, but they get about everything else.