I tried this once, with sliced banana in peanut butter oats. And my granddaughter, with the unfiltered honesty of a 4-year-old, told me it was “a little bit disgusting”. LOL. Basically what happens is the banana gets kind of slimy as it sits in the liquid overnight. So if you are picky about textures (which is everyone in my family) then I recommend you add the fruit at the time you are going to eat the oats.