I should also mention (and sorry for the multiple followups, but I can't for the life of me see how to edit a post here) that I haven't used any fuel additives. The engine does get worked reasonably hard however, and has seen the rev limiter half a dozen times.
I wonder if Toyota uses something which is Si based in some of their new engines. On my 07 Scion tC, the first OCI/UOA showed Si as 303. What did you do to address high original Silicone? When did you change the air filter?
As far as lead - I do not know.
I would try a different oil, maybe Pennzoil Platinum. Your flashpoint looks low to me so fuel dilution could be an issue. You might try Dyson Analysis, it's expensive, but worth the extra money.
