Combine all ingredients in an Instant Pot or Pressure Cooker.
Set vent to sealing position and set time for 1 minute on porridge mode (see note).
Porridge mode will naturally release the pressure on it's own.
Adjust consistency with milk once the oatmeal is done.
Sometimes the IP can give a burn notice when cooking oatmeal. I don't have this problem in my 6 quart but I have had reports of it happening in the 8 quart. The oatmeal will not burn, but it may be golden brown on the bottom. This is normal and fine.