For years, I subscribed to the "thicker is better" theorey, and I used Valvoline Racing 20W-50 exclusively (this is in a 327 Chevy II that only sees summer use). Now that I am older and wiser, I see no need for such a heavy oil. Does 20W-50 have any practiacl applications in todays motor oil market? While we are on the subject, what make Valvoline "Racing" oil different from thier regular 20W-50? I would typically run this oil for 3000 miles of street use with a PF35L filter. Never did an analysis though. I was under the impression that the racing oil has more Zinc. Is this true? Thanks.