I had more luck cooking them using a lower power setting. On my old microwave, I would use a 60 or 70% power and I could see how it would cycle the power off and on. What was cool was that it would cycle it off just as the oatmeal started to boil over and the oatmeal would calm down. When it cycled back on again, the oatmeal would start heating up again and just as it was about to boil over, it would cycle off. This went on for the entire cooking time. I got it to a point where I could cook 1/3 cup of oats, 1/3 cup of milk, and 2/3 cups of water for 8 minutes at 60% power. (disclaimer: I forget the exact time - I think it was 8 min.).