So we ran out of rice cereal and someone had given us oatmeal cereal but we have found that it does not dissolve as well and cakes up the bottle and you have to adjust the nipple. So now I'm wondering which cereal is best. Will the others do differently as well? How many different kinds are there? How are they made? Could they be contaminated with things he shouldn't have? Do you know any of these answers? if so please let me know.