With as I need it to walk or do anything strenuous. Even with that if a am working out too hard my O2 levels still drop real low and I need to stop and get my levels back up.

With. I used to be able to keep my saturation levels up without it, but as I've gotten older, I need 02 to exercise, especially to have any intensity to the exercise. I want my exercise to be as intense as I can manage, because that gives me the best bang for the time and effort it takes. So yes, I definitely use 02!