Today's passenger car motor oils are formulated to be compatible with your street car's emission control equipment, and Federal EPA requirements have led to a reduction in formulated anti-wear chemistries like Zinc, Phosphorus and Sulfur in API rated engine oils. As a result, the oil you buy today is not the same as it was 10 years ago. While this is good for your street car, it is bad news for your racing engine.
I switched to Joe Gibbs Racing Oil, my engine builder told me to run a blend. He said they had problems with straight synthetic oils. If you want any info on the oil you can e-mail:
markpow@powers-motorsports.com