Not directly related to racing engines with flat tappet came, but a friend of mine who is an engineer at Ford told me that when buying a new car, always change out the piss water 5w20 oil immedietly in favor of 10w30! The 5w oils being used in engine applications today are directly related to increased EPA mileage requirements, and offer almost no protection against wear, it's all mandated by HQ to fall under the ever increasing mileage standards put forth by the govt!!