As outlined, while the BG 20w-50 is a higher viscosity than needed for drag racing, especially for Stock, it may at least have higher levels of zinc & phosphorous most people recommend for older performance & race applications, as well as break-in. But you have to do some research to know which oils still have higher levels. "Shelf" oils for newer cars and diesels have had a lot removed and even some racing oils don't emphasize the ppm content.
It's explained a bit more in this Amsoil bulletin:
http://www.amsoil.com/techservicesbu...t%20Tappet.pdf
Of course, if you have Schubeck/Smith lifters, it isn't as critical.