For the 1999 and later 3 Series (E46), BMW introduced an extended oil change interval of approximately 15,000 miles depending on engine operating conditions. The introduction of BMW High Performance Synthetic Oil has made this longer interval possible.
1999 to 6/2000 models.
BMW uses a unique system to determine maintenance intervals. BMW's Service Interval Indicator (SII), calculates maintenance intervals based not only on elapsed mileage, but also on such inputs as engine speed, engine temperature, number of starts, length of trips, and the amount of fuel used. At the appropriate time, the system indicates, through lights in the instrument cluster, when the next routine maintenance is due.
6/2000 and later models.
For the mid-2000 models BMW introduced new service interval software which calculates service based on the amount of fuel used. When SII detects total fuel consumption that equals the preset limits (in gallons), the instrument cluster indicates that service is required.
Using a 328i as an example:
- Standard transmission model: SII illuminates after consumption of 601 gallons of fuel.
- Automatice transmission model: SII illuminates after consumption of 667 gallons of fuel.
After the service is performed the SII can be reset to zero.
The SII displays the mileage remaining before service is due. The type of service (OIL SERVICE or INSPECTION) is also illuminated in the display.
An OIL SERVICE interval will always be followed by an INSPECTION interval, which will then be followed by an OIL SERVICE interval, and so on.
When the ignition is turned on, the service recommendation and miles remaining are displayed for a few seconds. A flashing message and a negative (-) symbol in front of the number indicate that the service interval has been exceeded by the distance displayed.
The On-Board Computer uses the rate of fuel consumption in the period immediately preceding to calculate the mileage before the next service is due.