I don't know if this applies to the subjet, but I work at a power equiptment store and one of our customers used nothing but Mobil 1 in an 11hp. Briggs and Straton engine. Well this engine used commercialy will almost always be junk after about 2-3 seasons, his lasted 8 years and when the mower fell apart and he bought a new one I did a compression check and it was within 20 psi of new. Later I took this motor apart and there was no scoring on the cylinder, no sludge, and you could still see some of the cross hatching in the cylinder.I know it's not a car but after seeing this I was sold.I also knew a guy who told me "now I can't be shure if he was telling me the truth" that he had a chevy suburban with 437,000 miles with no motor work ever done to this truck, he had the oil changes done at every 10k.Who knows but I think synthetics definitely offer better protection than any dino.