I use Castrol 0w-40 mainly because of the fuel dilution and timing chain issues. Im not to worried about LSPI, I haven't found much for LSPI issues for the 3.5 Eco. I change at 5k intervals, but I have not done any UOA. I did consider using 5w-30 for the last OC I did just last week, but decided against it just because I have a jug of 0w-40 already for the 6th quart. I do use the 0w-40 vs 5w-40 just because of what Ive read on here about it being a "better" oil. IDK.... Interesting thread!