From a BMW service document:
SUBJECT
Engine Oil Service with CBS4
MODEL
[NEW]
E70, E71, E82, E88, E90, E91, E92, and E93 with the N51, N52, N52K, N54, N62TU, and N63 engines
[NEW] INFORMATION
With the introduction of the E90 also came the next generation of Condition Based Service CBS4.
The primary change from previous CBS strategies is that the oil service forecast distance remaining is calculated and displayed separately from the time-based or absolute service-due date.
The mileage interval forecast calculation by the DME is primarily based upon an actual fuel consumption variable, which reflects the current driving profile.
It is the total fuel consumption, and not the accumulated mileage, which influences when the next oil service will be forecast as due.
The displayed mileage until due is only a forecast, and begins to decrease at a quicker rate once the remaining percentage drops below 50%.
If the actual fuel consumption profile increases or decreases from baseline averages, the mileage interval forecast will effectively increase or decrease as well.
The learned driver profile (average fuel consumption) is also used to calculate the next forecast mileage after a CBS reset. For this reason, a starting point of up to 30,000 km (19,000 miles) may be expected for a vehicle achieving lower than average fuel consumption.
The oil service will also be forecast as due 24 months after the last CBS reset, and will prompt for the service if the forecast based upon fuel consumption has not been reached.
However, it is recommended in the US market to change the engine oil at least once a year. More details concerning the low mileage annual oil service may be found in SI B00 04 01.
The CBS intervals for other maintenance parts, such as the microfilter and spark plugs, are now linked directly to a multiple of the oil service. For this reason, it is important that the oil service counter be set to indicate the correct service currently being forecast.
The SBT 000104070 (Condition Based Service), SBT 000406148 (Modifications to Condition Based Service, and SBT 000206146 (CBS - E70/71) all contain additional information on Condition Based Service strategy and functionality.
WARRANTY
Information only
AWo