Here it is out of the book...

US Owners - Follow the Maintenance Schedule for Severe Conditions if you drive your car MAINLY under one or more of the following conditions.

• Driving less than 5 miles per trip or, in freezing temperatures, driving less than 10 miles per trip.<
• Driving in extremely hot (over 90 degrees F) conditions<
• Extensice idling or long periods of stop and go drving, such as a taxi or commercial delivery vehicle.<
• Driving with a roof rack, or driving in mountainous conditions.<
• Driving on muddy, dusty, or deiced roads.<

Note, if you only OCCASIONALLY or NEVER, drive under a "severe' condition, you should follow the Maintenance Schedule for Normal Conditions.

Now the question is what qualifies for MAINLY and OCCASIONALLY???