MikeMLS: I did not rank Pennzoil syn above the Mobil 1, Amsoil, or Red Line. What I was saying or ment to say was that would be my first choice between all of the Group III base stock synthetics. The Mobil 1, Amsoil, and Red Line are all PAO synthetics. What I call real synthetics. Completely different catagory as for as I'm concerned. We use to make a 100% synthetic called PERFORMAX. If we still did, I would recommend it above the others. It was a darn good oil. I'm sorry to say that our marketing department chose the way of Castrol.
You are correct about the flash point being left off of the spec sheets, and it bothers me. I have not gotten a good explanation as to why. The conventional oils are somewhere between 420F and 440F, and the Synthetic is somewhere between 430F and 450F. The High Mileage oils also fall within this range.