It was true that Shell Rotella had a fair amount of zinc in it at one time but they have had to remove a fair amount of it due to emissions compliance.
A fair amount? Exactly what is a fair amount? Puhleeeez.
This another myth popularized by the recent changes in contemporary engine oil standards. CJ-rated HDEO's still today typically contain around 1200ppm zinc - more than double the amount allowed in their ISLAC/GF-4/5 rated passenger car counterparts.
Look it up and find the facts, or spread the myths. You can get more in the Brad Penn and other specialized racing oils - at the double the price. Whether or not those boutique oils would be called for in the majority of our applications is very doubtful.