the noises you hear is the horses in your motor making power. oil makes in the inside of your engine slick so the horses have not footing/traction to make any real HP at all.

amsoil is good stuff...i don't use it cause i'm a cheap bastard...so i use the cheap stuff and change regularly.

 

i run my bike on car oil 10-40 and zmax and other ****. seems like you can put corn oil in the f4i and it will run. however, i remember when i was using valvoline 10-40 pertorlium the clutch was grabbing much better than on a synthetic blend.... im gonna switch back to valvoline next time around...

im my opinion, anyone that spends more than 5 buck a quart on oil is wack. unless you run your bike on track and you are racing for a trophy; i dont see the point........... huge waste of money.
dont spend money on something that does not appreciate you, like your bike or your woman........

 

Amsoil would be guilty of consumer deception if it was inaccurate.

 

castrol r4 suberbike fully synthetic