motor oil

whats this?
I just used a 20w50 semi synthetic for my bike i only plan on running it for about 2000 miles then i am gonna convert to full synthetic 10w50. expensive, but from what i hear its well worth the extra cost to be able to run it an extra 500+ miles without damage.
this is just from what i read i could be completely wrong and just fucked up my bike royally.
my .02