we tried the oatmeal it did not work that well. But after we did the pre-heat thing it was just fine. When we did rice, we put it and the water in a pan, heated the mix, preheated the thermos, the put the rice mix in and it worked fine.
Like a lot of stuff, we just played around till we got what we wanted.
I have to say that I almost fell out of my seat when I saw the price on some of them on Amazon, most over $200.00.
Greg