I'm not sure about regular oil but isn't the trick with synthetic that it doesn't breakdown? Well at least under normal driving and not as quickly. I decided after a few 5k oil changes to just go with the 7k change recommended by Chrysler.

It would be interesting if a purely objective study could/would be published without prejustice. There are so many studies, papers, articles published on the internet and in magazines that contradict each other it is impossible to make a true choice.

I've put 350k miles on a Dakota V6 and 210k on a Ram sport with oil changes at 3k +/- miles. Neither every burned oil and have had no engine issues. Could I have gone to 5k with regular oil? Who knows?