Oil is just Oil, unless you compare Synthetic to Dino oil.
I use Synthetic, and change twice a year. I change in the Fall to a 5W product, then I change in the Spring to a 10W product. Even the 2010 520i BMWs oil change interval flag is very 15k miles, and you must use Synthetic as called for in the owners manual. The best being the 0W40 by Castrol, made in Germany. Other Castrol weight oils do not indicate it is made in Germany, only the 0W40 does, that I have seen. I looked at all the other Castrol oils, all other blends and weights, none say Made In Germany except the 0W40 brand.
Still, even regular oil has come a long way in 10 years alone. My 2008 Pontiac Vibe manual says 7K interval with Energy Conserving 5W30, though I use regular, it is a company vehicle, they won't pay the Synthetic prices... Which is dumb, because you can go almost 3 times as long between Synthetic changes...
This is, of course, my opinion, and what I do, and is not a part of the 10 commandments. I use what works for me, and has gotten results, for me. You all can so whatever you want, with whatever you want.