One of the other threads has been covering viscosity improvers and use of lighter formulations. I went back and dug up an interesting 2014 article from MotoIQ, a site run by Mike Kojima who is one of the premiere import engine builders and has been for 25 years or more. I mentioned him in an earlier post. Mike had usually been an oil agnostic. As oils had "improved" over time he was less of the "only use Motul or Redline" kind of guy than most racers. The article and many of the comments in the comments section from other racer/builders were interesting with regard to additives and what is happening to oils as we go tighter and tighter on the emissions regs.
http://www.motoiq.com/MagazineArticles/I...enrite-Oil.aspx
http://www.motoiq.com/MagazineArticles/I...enrite-Oil.aspx