Synthetic Engine Oils
The 8.4L engine comes from the factory with synthetic engine oil. A full synthetic API certified engine oil of the proper viscosity grade is recommended for refill.
There are a number of engine oils being promoted as either synthetic or semi-synthetic. If you choose to use such a product, use only those oils that are certified by the American Petroleum Institute (API) to display the "Certification Mark" and show SAE viscosity grade recommended for each vehicle. Follow the service schedule that describes your driving type.