[68Biscayne427]

I'm no petroleum chemist but I think the single biggest thing you can do to protect your motor is to change your oil - often... My personal opinion is a lot of it is hype. I am sure some of the more expensive oils are "excellent" at what they do, but I don't race my car, I just drive it to shows and when we have sunny days. If I was racing then I would probably have a much different opinion.
Like you, I have used a lot of different oils in my cars and never has one bit of trouble. But one thing I did was change them often.... My $.02.