Oil level sensor?

[Courageous]

Anyone experienced an odd issue with the oil level indication like this?:

After start up the whirly wheel timer tells me to wait for the level. After a few minutes I get an indication "FULL" then some time later (like 40 miles or so) it drops to I suppose a "REAL" reading somewhat lower. Simple science tells me that if the oil warms up then the level would increase but the opposite seems to be happening. I suppose I have to replace the sensor OR is this a common behaviour?

Thanks in advance.

[biojo]

mine wont tell me untill the engines fully upto temp .

How long are you waiting before you try to test, when did you last have a oil change?

also thing of cars with dip sticks, u wouldnt check just after the engines been running as oil will be still in the head etc you wait for 10-15mins. BMWs system is opposite so car should have been running 15mins then check

[Mr Tidy]

Mine won't work until I've done 4 or 5 miles, neither will my E91 (same N52 engine).

[Courageous]

Yes that's not the problem, I wait until it gives me a reading. The problem is the difference between the two readings being illogical to my stupid head. Yes it's a few minutes, maybe 4 or 5 miles before I get anything. Why should it go from full to anything else like this?

[Courageous]

Thanks for coming in on this by the way.

[Smartbear]

Yes that's not the problem, I wait until it gives me a reading. The problem is the difference between the two readings being illogical to my stupid head. Yes it's a few minutes, maybe 4 or 5 miles before I get anything. Why should it go from full to anything else like this?

Hi, I think a few minutes isn’t long enough for the oil sensor to work correctly-my car takes a lot longer than that to give a reading.
Rob

[ph001]

I don't think there is any logical reason why the level would be different depending on the temperature. You do get a fair bit of difference between a reading with the engine off (i.e. the traditional way with those lucky enough to have a dipstick) and it running. This is primarily down to about half a litre running around the engine itself when driven by the oil pump. In the case of the N52 for correct oil level measurement, the following conditions have to be met:

"Fig. 52: Checking Oil Level
Courtesy of BMW OF NORTH AMERICA, INC.

Dynamic oil level measurement begins when following values are reached:
• Engine temperature > 60°C
• Engine speed > 1000 RPM
• Transverse and longitudinal acceleration < 4-5 m/s2

The transverse acceleration signal is supplied by the DSC. The longitudinal acceleration is
calculated from the speed and time factors.

On reaching this value, the oil level indicator is updated approximately 5 minutes after starting
vehicle operation. The oil level is then continuously measured.

The indicator is updated at 20 minute intervals."

[Courageous]

Thanks Ph001, that's useful stuff but not answering why I'm getting different readings after time. Still hoping someone else has experienced this or I may be looking at a new sensor. I did buy one but it was DOA so Mike at the ZedShed cleaned out the old one and got us to this point.