Please do a search here (you'll get everything from scientific analysis to links to oil websites and testimonys) and stick to the change intervals in your owners manual and you won't go wrong. Make your own informed decision and do what you feel is comfortable to you for oil grade and type. One person says one thing another says the opposite, its like a Consumer Affairs nightmare
An answer to this question is loaded with opinions, truths, lies, heresay, etc.
One thing does remain true through it all and that is engine oil is the life blood of your engine, take that how ever you want