I use Wesson cooking oil.
Just kidding. Listen, I realize all of us love our bikes almost as much as our children (for those who have children). That being said, we all want our engines to be bathed in a magical lubricant that will give us 1000hp and sunshine and birds singing will come out of the pipes at full tilt; and the engine could NEVER, EVER possibly think of wearing out while using this magic oil.
Here is what you need to do. Go to your nearest Wal-Mart. Buy ANY NAME BRAND oil in a 10w-40 weight (4 quarts), and a quality oil filter (yes I buy mine at Wal-Mart; a fram) and use it. Change the oil and filter every 2k-3k miles. I do this and my cost is less than $10. For that amount I can change my oil about 5 times a year; less than one oil change at a dealer. Your engine will love you for it.
Today's oils (conventional) are so good you will sell your bike to someone else for the next big thing in bikes long before the motor ever shows any sign of wear.
Synthetic oils are great, yes, but the only thing they really lubricate is your wallet, liberating more $$$ than needs to be!