Well, I can promise you folks the dealer doesn't care. At both Ma's Toyota and Caddy dealer and two different Hyundai dealers, I've gone strolling through the back lot. I'm looking for the tank they draw oil from. Without exception, they have lots of different stickers. Castrol, QS, Pennzoil. 5W30, 10W30 all with recent dating. I suppose the distributor's guy slaps em on. If it's not such a big deal for the dealer (and hence, the manufacturer), what's it matter to us?
Like Bill said, for 99% of the engines out there, what's it matter? "Optimal" is following the service schedule, and from what I can glean from the used oil analysis and the VOAs, the oil out there now in GF4/SM IS optimal. That being the case, buying cheap is the way to go. If you have a turbo, by all means, do syn. Long drains, use syn. But "optimal" is truly a state of mind at the current levels of quality. It's all optimal for most apps. Who's gonna argue with the used oil analysis after all?