There is an UOA in the Synthetic oil thread towards the end of it, like the last 100 pages or so, that in the same Truck Amsoil SS, Pennzoil Platinum, and Amsoil XL were tested in the same truck. The Amsoil XL looked pretty bad, and the Amsoil SS looked great as well as the PP looked great. I was able to find it, lol. edit..
Got lucky... Take a close look at the wear and miles on these oils. Look for the red that says which oil belongs to which column. Amsoil SS great, Amsoil XL not so much, lots of copper. Now, the XL was used in a early engine which could lead to more wear, but look at the different additives, SS is better plus is widely known to have a better base oil. Look at visc at 100, SS has a better visc eventhough both oils started the same weight 5w30 and high flash point= hints at better base oil. Most important, LOOK at the TBN. XL very unimpressive but Amsoil SS could go another 10k miles.
So what I'm trying to say this is my best case for you to step up to Amsoil SS instead of any of their lesser oils. It is worth it, the uoa's are pretty clear. You can run the oil longer as well, it pays for itself. That high Calcium, really allows you to easily go 5k more miles then any other oil Amsoil has.
