Hazardous waste is waste that poses substantial or potential threats to public health or the environment. In the United States, the treatment, storage, and disposal of hazardous waste is regulated under the Resource Conservation and Recovery Act (RCRA).
Porsche recommends that the oil in the Boxster be changed every 15,000 miles as a part of the normal maintenance procedure. The recommended oil is Mobil 1 comes in several different grades. If you wish to change your oil more often and want to avoid some of the expense associated doing so, you can change it yourself.
I guess I just know too much based on personal experience. Here are my revised oil change recommendations: Change regular petroleum-based oils every 4000 to 5000 miles and synthetic oils every 5000 to 7000 miles.