Comparing a harley motor to a benz motor is a bit of a stretch.Synthetics are definitely better.Thats why I extend the service a couple thousand miles.The crossfire manual is not clear on oil change mileage, its monitor starts at 7k but can go up or down depending on driving conditions.The 2004 Pacifica manual is more clear,it uses regular oil.The Pacifica manual says 3k oil changes and under NO CIRCUMSTANCES should the oil go more than 6000 miles.Going by my 20 years experiance I change oil at 3k and synthetic 5k.A couple years ago chrysler started stamping their factory oil filters with FACTORY INSTALLED so there is no doubt about the filter being changed or not.Oil changes are cheap insurance considering the price of engine repair.