All this extended range is rated on ideal driving conditions and driving practically non stop so that contaminating condensation is immediately gone and other combustion contaminents that are formed are rapidly burnt off rather than deposited in the oil. In most cases the daily drivers are relatively short drives and IMO requiring frequent oil changes. Extended oil ratings or not, synthetic or not. It is not the oil that goes bad but the contaminants that it contains that most filters cannot remove. Oil change frequency will depend on the type of driving being done during that changes duration. BUY GOOD OIL KEEP IT AND YOUR ENGINE CLEAN. It will lead to a long and happy life. Mopar recommends the same change mileage for either dino or synthetic oils in the owners manuals I have. Oil is still the cheapest maintainance item there is there is no reason in the world not to change more often.