I am curious as to where the extra lead could have come from. I realize 6 is still very low but I had none at all in previous two reports.
Blackstone thinks it may have come from fuel additive or race gas. I did put in a quarter tank of race gas after a gas station attendant accidentally put in 87 octane right before an autocross event.
But the race gas was 100 octane unleaded. (It was supposed to be, at least).
Is it possible that even unleaded race gas could contain small amount of lead?
Particle streak on a bearing? (Blackstone doesn't think my engine uses lead bearings but I asked on an enthusiast forum and the people there think it does)
Just an outliner that I should stop caring about?
BTW this sample saw heavy autocross use (almost every weekend Oct-Nov and then March-June). Most of the miles were from driving to and from autocross events. Lots of idling while in grid.
Car sat in the garage from late November to late March if that matters.
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