As Bill said, sodium is part of the additive formulation in GTX and Syntec Blend. The results look very good to me. I had a random spot of Tin show up when I used Pennzoil Platinum last winter and I haven't had it repeat itself. Wasn't really sure what to think of it, but the car's still running strong. I ran Syntec Blend 5W-30 for my last oil change and I wish I would've gotten a UOA.