Radiator Pressure Cap: Cleaning
WARNING: This page is about a different car, the 2006 Dodge Magnum, 2006 Dodge Charger, and 2006 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
Use only a mild soap and water to clean the radiator cap. Using any type solvent may cause damage to the seal in the radiator cap.