so i just read all the posts on this. and the thing that i notice most? if it had been any oil other than amsoil, a lot of folks would be jumping up and down saying 'here's your proof', but since its amsoil, well, there must be something else wrong. syn3 (or insert any other brand here.....) is thin, bad oil. amsoil is thin, and you're immediately asked if your eyeball is calibrated for viscosity.....
like mentioned, i don't care for their pyramid like sales, their own testing, and the fact that they use tests that no one else does. and i believe that most oil co. will warrant your repair if it is due to an oil failure, so that really doesn't make me have extra warm fuzzies for amsoil.
the best policy is to use whatever you are happy with using, but change it on a regular basis (i use mfg suggested intervals) and the odds are very much in your favor that you will not have an oil related problem with your bike.