Well, let me first say that I am not an oil tribologist or an expert in that field per say. I will say that I have made my living buy running/owning repair shops for about 23 years.
That being said, I have run the Schaeffer oils in several of my customer's cars and all of my personal rides as well as my operating farm's trucks. I spent the better part of three years trying different oils for about a year before settling on Scaheffer oil.
Lead numbers in several of my and my customer's rides are not high. Rather they are higher than what we saw with other brands of oil. I have heard the statement that it was coming from rod&main bearings which is completely false. My shop repairs primarily Asian Import cars&trucks and they have,at least since the early 80's used one piece high-silicone aluminum bearings in all their engines.I don't care if it's a Honda,Toyota,Nissan,Subaru,Kia,Hyundai,ect... they do not have a tri-metal style bearings in them. All of your major domestic engine makers followed suit by the early 90's. It's all silicon bearings now. Even if you had an old American car that did use the old Clevite-designed steel-lead-aluminum bearing if the lead was coming from the bearings you would see some serious aluminum numbers as well. The fact is that the wear numbers on MOST Schaeffer UOAs are pretty impressive for what some would say is not a "true" synthetic. So, where is the lead coming from? I am inclined to believe that it is part of their anti-wear package. I can understand the interest in the lead but you have to remember we are talking about ppm here.
I have it in a $100 Corolla that I got from a customer. She did not know that oil changes were a part of taking care of a car and she spun the bearings on the crank at 150K miles. I put a crank kit in it,new rings,valve-job and have run it like I stole it. It now has 187,000 on the thing and uses no oil on Schaeffer 5W30 every 10K miles. This car will run on the Schaeffer oil exclusively for the next 100K and then I am going to pull the oil pan,drop the main&rod bearings for all to see. With my daughter running it back &forth to college it won't be much longer.
My point is that IF the lead was coming from a bearing you would have some serious problems becouse the lead layer is the center layer of one of those old bearings. It is completely encased by molten aluminum during the forming process so I can't see it leaching out. Further, I can't see anything so radicle in Schaeffer's formulations that could dissolve lead to begin with. I think it's something in their formulation when mixed with other by-products of combustion that shows the higher lead. I could also be completely wrong. I have been before,and will be again. This one thing I do know after running alot of analysis on my stuff over the last three years.
Schaeffer makes one heck of an oil for it's price. I'm not saying it will always run out as long as some other oils but when you compare it's price to the service it renders, it is hard to beat. I 've quit running UOAs on my stuff now. I pretty much know how long the cars,trucks,tractors I have will go safely and I just change it then. Granted, doing UOAs is fun but there's been alot of good oils slandered because someone ran one,two, or three oil changes and tried to make a determination from them especially if the ride was purchased used,or ran on whatever dino oil was avalible, or had previous mechanical problems. I found that on my used stuff, the longer I ran Schaeffer the better my UOAs were and the longer I could extend the intervals. That's true with any good synthetic such as Amsoil,Redline,RoyalPurple.
After saying all that,I still ain't sure about the lead but it's not an issue with me anyway. Schaeffer has proved itself to me.
Are you running any type of fuel additive in the engine? Alot of them do contain lead and some diesel comes with lead in them as a anti-wear additive. That could skewer the numbers some. If the engine does have a cooler on it it has some lead in the construction.