The sythetic, from what I have heard, only really helps on startup. Standard oils contain parafins (aka Wax), When the car settles down to cool temperature the waxes crytalize. Then when it comes time to restart, the oil pump has much lower flow because of the wax, and your pistons/bearings/turbo do not get oil as much oil as fast, generating friction and wear. You ever hear 90 of engine wear occures on startup, this is why.
Now not to get off an a rant here, but if some manufature were to mandate synthetic, and use Dana's electric oil pump to get the oil flowing prestart, ie when you open the door or use the keyless entry, then maybe the wear could be even more reduced. The problem is that if they figuired out they had less wear, they would simply thin out the cylinder linings such that the car would still die at100kmi Bah, I hate the auto industry.
Tour:
My dad has had three dodge caravans 83-3 replaced headgaskets 89-2 replaced headgaskets-head warped 96-5(No joke) Transmissions (No engine problems ran Mobil 1). I had a 90 Plymouth acclaim, 2-blown headgaskets, head warped. See a pattern here? My dad didn't ,he finally bought an 03 honda oddity, AFTER the dodge he was test driving, wouldn't start and the sliding door handle broke off. Point of the story dodge cars are crap imho, except for the new trucks (.88g lat and a 345hp hemi in a pickup!), the jeeps(only cars DCS liked), and the new DCS cars (ie Pacifica). And, even the pacifica maybe bad, I mean look at the M-class.
Yes oil makes a difference, but mostly the engineering is what kills ya (no pun (or pinto) intended), and you will not find cars built to last, they are built to be replaced. It simply costs too much to make them last, and even if you could you couldn't sell the fact that your cars would last to 300-500 thousand miles, who would want a car that long, I mean the time it would be dying it would be coming right back into style.
Personally I run Mobil 1 0-40, I have a Contour SVT, my oil changes cost me ~$40-50 6 quarts + filter + $10 dealer inspection and oil change. I bought it because it was designed accross the pond, but unfortunately it was built over here, every problem has been a bq/manufaturing/cost cutting issue.