The question of oil (brands and viscosity) and additives (included in the oil or manually added with an oil change) is in my experience (which goes a relatively long way back) a topic that brings out deeply rooted personal opinion and preferences.
I remember conversations between my father and his best friend about the advantages of single-weight versus multi-viscosity oils. They were at opposite ends of the debate, so the sessions were lively ones indeed.
For the first time in my piston-engine aircraft experience, I've got a factory new IO-360 with mineral oil for the break-in period. I didn't have any at the hangar, so I began looking for some and a fellow aviator happened to mention "The Mineral Oil Myth." I researched it and came away with the conclusion as stated by more than one engine manufacturer rep, that engines have been and will be successfully broken in with straight mineral oil or ashless dispersant types.
More to the point in this discussion are articles by Mike Busch, who supposedly is operating a single and a twin with engines that are about 900 hours past TBO. I've been told he's doing this with strict adherence to the principle of LOP operation, Phillips X/C 20W50, and Camguard. One of his key points is that with Camguard, there's no reason to pay the extra for higher priced oil.
I don't have the expertise to comment on the validity of that opinion, except to say that I've used Phillips exclusively since 1996 or thereabouts and have no reason at this point to suspect that it has negatively affected the condition of the engines on any of the three airplanes I've owned. I began using Camguard about two years ago because it seems like a really good idea.
And there you have it, a feel-good reason that hopefully is based on scientific fact and not old wives' tales.