I think the TBN was helped along by the residual magnesium compounds left behind from the previous run of Edge. I also think that some of that iron is also a carry over.
I am not overwhelmingly impressed with the results for Castrol oils in this GM Atlas motor. I didn't like GTX HM in my Trailblazer's 4.2. It was great for about 2000 miles, then things started getting really noisy. OEM PF61 classic filter.
Castrol SynBlend for the first 2 and Castrol Edge for the 10k run…
Haha, Mobil, good one …
Comparing same mileages to my 2005 3.5L the iron number are very close (except for the 10k run @ 49) and seem to be on the same upward trend.
i ran Mobil in my 05 for over 138k miles, so i'm giving Castrol a try, was hoping to see a little better results also. back to a GM PF61E filter … thinking the same thing about TBN and iron, will see on the next test...
Blackstones comments ...Nice turnaround! There's nothing highlighted to talk about here. Aluminum has dropped back
down to normal, and while iron is a bit higher than we were seeing back in 2013, it is reading within the
average range now (and that counts for something). Maybe it'll improve again next time. Sodium is back
down to normal as well, and no fuel or other contaminants were detected. The TBN is back above 1.0,
reading at 1.4, so there's still a sufficient amount of additive left in the oil to run longer. This 3.7L is looking
good at 55,500 total miles
What is going on with that high iron? I'd get a strong magnetic (not the cheap ones) drain plug on there to see if you can collect iron filings, at least that will tell you if something really odd is happening, and get some more out of circulation. GoldPlug.com is a strong magnet (I have one), and I think there's one other, DrainPlugMagnets.com for quality stuff. Avoid Dorman or other cheap, weak magnets.