I have heard the same thing about using synthetic oil during engine break-in, and it does make sense. Another factor to consider is the engine oil will be changed quickly during engine break-in, and one doesn't need to spend the extra money for the long-lasting qualities of synthetic oil until the break-in process is completed.
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Spud
"Never argue with an idiot. He will drag you down to his level, and beat you with experience."
Mark Twain
2015 Zongshen ZS250GY-3 (RX3)
2006 Zongshen ZS200GY-2 (Sierra 200)
2005 Honda XR650L
2004 Honda CRF250X
1998 Kawasaki KDX220
Mods made to my Zongshen ZS200GY-2:
http://www.chinariders.net/showthread.php?t=6894