My understanding (which could very well be incorrect) is that longer oil change intervals are better for the environment (less oil waste), whereas shorter oil change intervals are better for the engine, and the Toyota engineers have worked hard to design the engine to be able to *handle* longer oil change intervals, even if that's not what's *best* for the longevity of the engine. I figure that it's an optimization problem to determine what is best for your purposes for your vehicle, your finances, etc. etc. Since I'm aiming to get 300k miles or more out of an engine (and I do the oil changes myself so I'm essentially just paying for oil and filter), I'll go for the shorter oil change intervals, especially since the 0W-20 oil is surprisingly dark already at 5k. Is it absolutely necessary? Yeah, probably not, but I do feel that it will contribute enough to a long-lasting engine for it to be worth it to me. For someone who is planning to trade in their car at 100k miles or so, I'd guess it might be rather pointless to do shorter oil change intervals. But again, personal choice. And I agree that data from a Blackstone Labs report is very, very useful. That reminds me, I should send them another sample next oil change...