Due to having 15 quarts of oil the recommended oil change period for the 930 is around 9K miles.

That being said since my car was a bit souped up and driven hard I changed it every 3-5K miles.

There are some engines out there, such as the toyota 3L V6 and the chrysler 2.7 that have oil sludging problems due to oil stagnating on the hottest area of the heads.

In many cases of sludged up motors this is the cause instead of lack of maintenance.