Good Dispersant/Detergent Qualities
WARNING: This page does not describe the selected car, but rather 250 other vehicles, including the 2006 BMW Z4, 2006 BMW X5, 2006 BMW X3, 2006 BMW M6, and 2006 BMW M5. However, it is still accessible from the selected car via links, so may be relevant.
To limit or slow down the formation of combustion deposits and acidic components, together with abrasive particles and dirt from the intake air, good engine oils contain a detergent additive. Deposits of carbon and dirt are loosened and suspended in the oil, being drained away at the next oil change.