Oats- Gluten-free or not?

There is great controversy about whether or not oats are gluten free.  The abbreviated answer is “yes” and “no”.  It seems oats are naturally gluten-free, but have often become contaminated, during growing and/or processing, by contact with other grains.  Some people who are gluten-intolerant find they don’t have any problem with oats, while others find they have a reaction to them.  It used to be that a person had to test them for themselves, but in more recent time (hurray!) some manufacturers offer certified gluten-free oats.  The only drawback is that they are rather costly.  A friend whose son has celiac disease said his gastroenterologist indicated that Quaker traditional rolled oats are gluten-free, though they aren’t marketed in this way.   I wonder if this is because their machines are dedicated to only processing oats.  There may be no way to find a definitive answer to this, but it may be worth testing them for yourself since they’re substantially cheaper and easier to find.