Gotta reply to this one even though the thread is a bit old. Sulfated ash measures the metal content of the oil. The sulfur here comes from the sulfuric acid used during the sulfated ash analysis - not from the oil.
Most sulfur in an oil comes from the ZDP, some comes from the oil itself, and some comes from the detergent or other components. In general, the higher the ZDP level, the higher the sulfur.
That said, the ballpark range for %S is ~0.3 to 0.8%.
Excellent information - thank you. Would diesel engine oil contain a similar amount? Also, is there an approximate correlation between how much zinc is in the sample and the amount of sulfur?