Oh, I also know of another mechanic with over thirty years experience and he says that the top three conventional oils are Valvoline, Mystik, and Chevron. Kind of hard to agree with that Valvoline choice, based on what people here have discovered. On the other hand, there are a HUGE number of professional mechanics who swear by Valvoline. Based on what people have discovered here, you would need to add the Valvoline Engine Protector to conventional Valvoline to bring it up to the others, unless we are missing something.
I am guessing that professional mechanics have been influenced by advertising when it comes to Valvoline. I know I was-I switched to Valvoline because so many mechanics said it was great.
I know of still another mechanic who specializes in small cars who tells people to use Valvoline in cars and Mystik in big trucks. It is rather amazing that Mystik seems to be so well known by mechanics, considering that it is hard to find in most stores.