Oil is a interesting and often heated topic. There seems to be good and bad points. I have used synthetic in my Pontiac with no problems. Zimmerman Brothers Racing said they were able to get 7 horse extra from synthetic.
One question that was asked earlier but never answered. Why do some camshaft manufacturs not recommend synthetics. Here might be some answers.
Use of Synthetic Oils
Crower does not recommend the use of synthetic motor oils in any racing applications, particularly hydraulic and flat tappet camshafts. The minimum gains in horsepower are offset by the excessive wear to cam and lifter surfaces. Crower recommends Kendall GT-1 (20W50) Petroleum based motor oil in all high performance applications. If your manual suggests running synthetic oil, then do so. We have found, however, that the benefits do not outweigh the costs. For additional information click here!
http://www.atis.net/oil_faq.html