Agreed, we can walk further than running.
As I'm sure you're already aware this 6 ppm Al was flagged b/c it doubled Blackstone's Averages & they have some decent advice to follow. In general the oil is capable of handling this 6ppm Al so that is not a concern as long as it's not adding to any additional wear to your engine.
Your engines Al does display some extra wear, then past UOA, that needs to be trended further. You could heed BS comments & keep costs down by running any oil for the same duration to check up on the Al. Then make the decision to go back to HPL once those results come back ok.
Essentially, it doesn't appear you're having additional wear due to the extra Al in the oil. There may be a point to which it does contribute to wear but it doesn't appear here yet. The Al is probably from pistons as previously mentioned by other posters. With the mileage you have on this unit, most likely not having a rebuild yet, It may be the rings are worn & causing the Al piston wear.
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