Anyone Know What This Maintenance Reminder Is For?

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While we are at it- same article, different sensor:

Voelker Sensors Inc. Oil Insyte
The Oil Insyte sensor uses a patented technology based on the electrical properties of an oil-insoluble polymeric bead matrix (see Automotive Sensor Technologies Explained below for more details). The Oil Insyte employs an in-line method for continuous oil condition monitoring with an LCD readout providing detailed information about oxidation, additive depletion, soot contamination and oil temperature. The technology does not require external calibration standards and reports oil condition independent of viscosity.

According to the manufacturer, the sensor measures key indicators of oil degradation and allows the conventional analyses approach of oil monitoring (sampling and analysis) to be combined into a single more efficient analysis. No assumptions are required as to the condition of the engine or the initial baseline quality of the oil.
The Oil Insyte technology measures oxidation and additive depletion, and has the ability to examine the interdependence between the two. They claim difficulties encountered with sensors that measure only the electrical properties of oil (conductive additives masking the true condition of the oil) are overcome by using a differential technique where the conductivity of the bead matrix is measured relative to the conductivity of the oil. The true polar condition of the oil can then be determined.
The soot detection feature of the sensor determines the amount of undispersed agglomerated soot (vs. dispersed finely divided soot) present in the oil. Depending on the oil’s additive package, the same amount of undispersed soot can be present at 1 percent to 2 percent (for the base oil without dispersants) as a fully formulated motor oil with more than 7 percent soot.

Sounds a bit different than the BMW.continental sensor.

Say, I wonder if there IS some method to BMWs madness that ONLY BMW oil be used...so the sensor has a known baseline?