[SwissCheeseHead]

I'm sort of questioning the CBS monitoring due to this sequence of events. Acquired a 2011 328i Sportwagon in Feb 2013. Got a dealership oil change in July 2013. Questioned the dealer about the length and time of oil change intervals in Feb 2014. Oil was about 7K miles old. Did an oil change at home with Wix filter and Mobil 1 0W40 (Feb 2014). Get a "service" indicator in over the weekend (May 3rd, 2014). Bring the car in to the dealer and it indicates that I am due for an oil change.

Oil is only 2 months old and not even 1K miles on it. Is this truly ondition based or some BMW gimmick to make their technology seem more fancy than it is?? I have a really hard time believing Mobil 1 full syn has already broken down that fast that I would need an oil change already.

Thoughts on the validity of CBS? I'm still planning on changing it every 6 months or 5K miles.

[PhaseP]

Did you get the oil interval reset when Mobil was put in? Did dealer reset the interval when they changed in July? (CBS wasn't due so they may have forgotten to reset it). If both reset was not done, by May 2014, computer was thinking that you had the same oil for 15 months, gives warning time for a change, regardless of condition of the oil.

The books says not to go overy a year without a change of oil yearly even if CBS warning doesn't come on, which happens with light usage.

[biscut]

+1 on the reset. You can be assured, barrign some catastrophe at Mobil that their 0-40 would not be depleted at 1k.

[Crusader]

The system does not do an oil analysis to determine you've replaced the oil, so without a reset it will continue to act as if the oil is xxxxx miles old (there are some tricks involved with the sensor that might modify the result slightly involving its electrolytic properties).

The 1 year service is a good guide. Low miles per year generally equate to multiple short trips; lots of highway miles has lesser impact per mile.

High quality synthetic at the proper viscosity changed at reasonable intervals for the car's service will just about guarantee the engine will last well beyond your ownership.

[PhaseP]

If I remember correctly the sensor is a capacitor whose value changes with oil property, something like that. So CBS determines based on miles used and the sensor reading.

[Efthreeoh]

OP, the CBS system determines the oil change interval using an algorithm that considers many variables including the oil quality analysis the oil level sensor performs. The algorithm uses metrics such as fuel consumption, engine warmup interval, cold starts, time, and several other metrics along with the oil quality input from the sensor. As stated by others, the oil quality sensor does not determine when a fresh load of new oil is added to the engine. You have to reset the CBS when you change the oil so the system knows when the oil change was performed to start the OCI calculation on the new load of oil.

Once the car reaches 186,000 miles the CBS is programmed to stop using the oil quality input from the sensor, and around 220,000 miles, will only reset the CBS to a 0 (zero) OCI - it then starts to count backwards and tells you the car needs an oil change every time you start it. When the car gets to this level of mileage and stops using the input from the oil quality sensor, BMW recommends reducing the oil change interval to 7,500 miles.

[SwissCheeseHead]

Thanks for the info. If you don't mind me asking, how do you do an OCI reset? It makes sense that if the interval was not reset, that the car thinks there is old oil in it. I still plan on doing the oil changes 2x a year because running it for longer than that seems to long for me, even if the computer thinks it's not.

[PINeely]

Originally Posted by SwissCheeseHead

Thanks for the info. If you don't mind me asking, how do you do an OCI reset? It makes sense that if the interval was not reset, that the car thinks there is old oil in it. I still plan on doing the oil changes 2x a year because running it for longer than that seems to long for me, even if the computer thinks it's not.

Turn on the car but do not start it, once all of the lights/messages have turned off press and hold the odometer reset button, you will see a warning triangle, keep holding it and a picture of an oil can will come up. Hit the "BC" button on your blinker stalk to select and reset it

[SwissCheeseHead]

Great. I'll keep this in mind for next time.

[BashShah]

Google e90 or e92 reset.
There is a great DIY on YouTube.
It will also tell you how to reset more than just Oil.

DN