the only real difference in synthetic oil is that the "oil" molecules are manufactured to a higher standard. However, since synthetics are usually sold as premium oils, they also usually carry a more expensive load of additives
, and it is the additives that fight corrosion and do all sorts of other good things. Mobil1 contains a lot of moly (molybdenum disulphide?) which is an excellent metal-on-metal lubricant. Kendall is pushing some mystical titanium coating, claiming it titanium plates metals in the engine. But the stuff that fights acids, etc? Harder to quantify, but since they are pushing longer oil change durations, they would have to put in more additives to cover the longer oil change period. In theory.
More good reasons to do an oil analysis. It may run $25 a shot, but one baseline, and then one a year later to see if you need to change oil more often or less, isn't a bad investment considering how many oil changes or engine jobs it may save in the longer run. Anything else is basically shooting craps.