dparm, I was replying to you :-) I have found the characteristics of you sensor:
BMW oil condition sensor
I have asked in BMW forums but there was no valid answer most people just said "why?". I was asking the wrong question.
SuperDave456, you got me on the right track. The oil filter...
The E46 seems to have only an oil level sensor but the E90 it does provide information on oil aging:
"BMW’s “Condition Based Service” (CBS) system monitors various maintenance items, and alerts you when service is needed. It is found on 2002 and newer 7 Series (E65 & E66), 2004 and up 1 Series...
I want to install an oil quality sensor (density + viscosity + temperature + humidity) to monitor online the lubrication the oil in my car (BMW series 3 E46), save the data and see the results online in my phone. A lab analysis tests many more parameters but those 4 are fine for me.
The tech...