AC Delco filter (Hengst). 31,556 miles total, OLM read 14%. Mixed highway/local use, driven gently by my own dear mother, haha. Disappointed to see the metals in the oil still, though trending down. My 10' COrvette has done the same thing. Several oil changes in, I still see significant iron in the oil analysis, but trending slightly less with each change. I guess these newer GMs just take years to break in.