What kind of oil does a 2003 harley road king take?

A 2003 Harley Road King typically requires 20W-50 weight motor oil specifically designed for V-twin engines. It's recommended to use oil that meets the API (American Petroleum Institute) classification of SM or higher and is suitable for air-cooled engines. Harley-Davidson also offers its own line of synthetic and conventional oils which are tailored for their motorcycles. Always consult the owner's manual for specific recommendations and maintenance guidelines.