I would also assume that if you run any engine on synthetic or conventional and you run any engine short on oil, you will damage the bearing surfaces.
As far as the demonstrations go, I have not seen one yet that isn't a "sales" tool for a specific product, and tend not to believe them or rely on them completely.
I remember one demonstration where the guy ran the engine without any lubricant in it for 5 minutes. He adamantly wouldn't run an engine with "straight" oils for any length of time. I asked him to run the "treated" engine without its oils until it stopped to see how long it would last. It lasted 18 minutes and some odd seconds. The salesman rejoiced that it was a miracle that the engine ran that long.
Shoot, we had contests when I was in high school to see how long an engine would run after draining the conventional oils. I remember 21 minutes and 34 seconds on one of them because I sold the winning ticket to my buddies father.
I started using synthetics on my tractor when in sub zero temps the oil filters would blow. I noticed that after I switched, not only have I never blown another oil filter, but the oil pressure stays consistant when the engine starts cold or is running at operating temp.
I don't use synthetics on everything however. Many times I don't get the miles on the vehicle to warrant synthetic use in them. I use synthetics in my newer vehicles that I drive every day, and my tractor of course.
