This is from the September or October 2002 Popular Mechanics magazine:
http://popularmechanics.com/automotive/auto_technology/2002/8/motor_oil/index.phtml
There are four pages to this article selectable at the bottom of each page.
http://popularmechanics.com/automotive/auto_technology/2002/8/motor_oil/index.phtml
There are four pages to this article selectable at the bottom of each page.