um, i use mobil1 full synt.

Something about it sticking to metal better helping eliminate dry starts which is #1 cause of wear.

i believe thats why GM recommends Mobil1 for their corvettes because national average on mileage driven on a C5 was 6000miles a year? Sooo, they would rather let the oil stick to the matel internals than it fall into the oil pan when the car is sitting in the old man's garage for weeks. Heard about it from my GM tech from school.

try this trick:

Get a flat head screw driver. Get a thing of regular oil on the tip and try to hold it by pinching it. Chances are, you'll be holding it.

Now try it was syntethic. Chances are, it'll slip outta your fingers.

I tried it in automotive class and its true.