With oxygen (2.5 liters while at rest), I am okay. However, once I start moving around, even as little as walking to the bathroom and back to my bed room, O2 level will fall into the mid 80's. Strenuous exercise make it plummet even farther. I require 4 liter/min for walking. So, anyway, your O2 levels are very good. I hope they stay just the way they are!