MOst people never put enough miles on their bike to find
out if their maintanence is helping or hurting.
Under normal conditions, changing oil and filter every 2k miles.
you can pretty much use whatever brand of oil K-mart has on sale.
Your bike will last as long and run as well as the next guys.
There are a few circumstances where you might want to step up
to a true PAO synthetic like Amsoil or Mobile1, especially when
they're cheaper than the "motorcycle oils."
For instance:
If you commonly start your bike when there are icecycles hanging
from your speedometer. (I do)
If you've ever cracked an oil line and had to ride home with
maybe two quarts of oil left in the engine. (I did)
If you just like they way your bike shifts when using a
particular brand of oil. (I actually don't care but others here do)
If you put 15 or 20 thousand miles a year on your bike and
really dislike changing your oil ever 3 weeks. (I DOOOOO!!!!)
And if you're a cheap SOB. (I AM)
I had 37000 miles on my oil and filter at the last change though
if truth be told the filter probably should have been changed
somewhere between 25k and 30k. Oil tests showed the oil
to be in excellent shape(viscosity essentially unchanged) and
only a couple of comtaminant levels hitting border line because
I pushed the filter a bit to far.
Now if you change your oil every 2k then you don't really need
an oil this good. On the other hand if you're paying much more
than $20 for a gallon of dino oil and a filter then you're probably
getting ripped off.