Hi fannystreisand.
Can I ask if you are doing rolled oats or real oats? If it is rolled oats then they take so little time on the hob the hob (or microwave) that I am not sure what you are trying to gain. They are steamed and flattened which partially cooks them and because they are thinner the final cooking is quicker too!
If it is real oats as in steel cut oats or pinhead oats or coxxxx oatmeal (all the same thing more or less) then that is a different matter possibly. As they are the whole oat grain chopped into about three pieces, they need longer cooking times of about 20 minutes with lots of stirring towards the end.
I am diabetic and food such as oats are very good as they are low GI and slow release as well as filling. I tried all ways with various size slow cookers and gave up in the end. It nearly worked perfectly but towards the end when the grain is beginning to break down and goes a bit gooey the stuff foams up and after a few times of cleaning up the mess I gave up. I even tried putting the slow cooker on a timer which was a little better but a real faff.
Another technique is to soak the oats over night in cold water in the pan - ratio of one part oats to four parts water by volume. You still have to stand and take care of it by stirring very frequently but it is quicker.
Now what follows might seem like even more of a faff but if you read it through you can see that it takes only a few minutes of your time in total. It takes around about 2 and a half hours of real time from starting to the porridge being in the fridge for the next day(s).
I hit on a different method by a bit of trial and error. Take 125g - 130g of the pinhead oats and add it to 900 ml boiling water from the kettle. Add salt to taste at this point if you want. Give it a stir and bring it to the boil and keep it at a moderate bubble. Make sure you keep near the pan so you can keep a close watch on it. Stir it frequently and cook it for 7 to 8 minutes. Be particularly careful about stirring it in the last 3 to 4 minutes. Turn it off give it another stir and cover it for about ten minutes. Another stir and cover again for about 15 minutes. Stir again and now cover for about an hour. Stir it again and I put it into three 350ml clip and lock boxes and leave to cool.
Store in the fridge and that is three healthy breakfasts that you can have as it is or add fruit, seeds etc. I usually find I need to sometimes add just a little more water or milk when I am heating it up and I usually do it on the hob, about 3 minutes is what it normally takes.
Cheers
Terry