Remember also that oil is not just a lubricant but a coolant also when you start thinking about the weight of oil.
Go to this link and do some reading. There is a lot of good info here. Check out some of the article and tech items on the left side of the page.
http://www.drivenracingoil.com/dro/zinc-vs-detergent
From what I have gathered on the Brad Penn oil, the amount of ZDDP in the racing oil hasn't been decreased. Just their high performance street oils.
http://www.penngrade1.com/CMSFiles/F..._BRAD_PENN.pdf
I have used the Amsoil Dominator racing oil, running Methanol and have been very happy with it myself.
Curtis