1) To the people questioning synthetic, I have to laugh. What's next...FI is a lousy technology and crank seals should still be made of rope? Cold performance alone is reason enough for me to put syn in things I plan to keep, plus oxidation performance at elevated temperatures is far superior to dino oil
2) IMO, any full quality synthetic oil is going to be better than a standard petroleum/syn dino blend. That opinion is based on things I've read, various oil analysis readouts, and real experience with various oil testing equipment (four ball wear, saybolt viscometer, etc.). There's a reason (numerous) why OEM's are moving towards synthetic in more and more new engines, and there's also a reason why many fleets run it.
3) To the people questioning Amsoil - is the cost worth the payout? I'm not sure. I don't sell Amsoil, but have used it. Their 2 stroke saber oil does what it claims....half the oil and still makes the engine live. That said, there are plenty of positive reviews of Amsoil by non-bias second party reviewers out on the web. Is it worth the extra $$ over say mobil 1? That I'm not sure of. I believe that there are far too many other variables that play a role in oil life degradation to simply state "brand x is better than brand z."
And also, some have said Amsoil spends way too much $$ on marketing....have you looked at Royal Purple
Again, they may be good products, but I think there are other brands just as guilty of advertising.
Bottom line, I'll take any
good group IV synthetic over a petro based oil - amsoil, penzoil, RP, M1, ashland, castrol, motul, klotz, shell, etc. Buy what you can get a deal on and change it regular interval based on your