Gents, I'm going to post this and I hope it does not start a big controversy (I don't think it will here, but probably would other places).
I've been following Richard Flagg on YT for over a year now. He is a small engine mechanic (in Georgia I think) and has a lot of good nuts and bolts chainsaw content on his channel. Over a year ago, he started posting that he was noticing that engines run with Stihl Ultra oil (the $pendy stuff in the silver bottle) had bad carbon build-up and seemed to lack much of an oil film on the crank and piston when he would tear those engines down. That kicked off a year long odessey of him doing some redneck testing and observation of oils and chainsaw engines that came thru his shop. He has numerous engine teardowns showing what various oils do in various saws. As a result of what he was showing, I switched away from Stihl Ultra, first to Red Armor (high detergent properties) and then to VP Racing two stroke oil. Subsequent to that, what he seems to have figured out is that two-stroke oil bottled and marketed to motorcyle folks is not only less expensive per mixed gallon, but has much better oil film/cling properties and very good detergent packages. Once I run through the VP Racing oil that I have, I'll be switching to probably the Honda oil that he tested. Bel Ray was another good one and there were a couple of other good ones.
Note: Flagg's bedside manner is a little gruff, I guess. Enough that I had discounted much of what he said early on. The more I paid attention to what he was posting, the more I realized that he is probably right and has no axe to grind. His observations are not scientific, but he seems to see a lot of saws come through his shop. If you take the trouble to watch *all* the videos he posted about oil, you will likely come to the conclusion that he is not just talking out his ass.
This video is pretty much the culmination of a year's worth of paying attention to how various oils behave in chainsaw engines. Lastly, I started running all my saws at 40:1 instead of 50:1. Flagg commented somewhere along the way that 40:1 is so manufacturers can make the hack with the EPA; it is not for the longevity of the saw. Made sense to me and I switched several months ago. So far, so good.