oil level warning light

[Flight]

Hi everyone.
Having just wakened my 3.0i from her winter hibernation, I was reminded of a little anomaly which I noticed last year, but forgot about.
The car started immediately, and ran sweetly. However within a few seconds of starting the oil low level indicator lit up, although the oil pressure light was extinguished, it remained lit for perhaps 5 seconds then went out and stayed that way. I suspect a sticky float switch in the sump. I am sure some of you good people out there will have experienced this anomaly, I would therefore like to take advantage of your knowledge before investigating further, any help would be appreciated.
Many thanks
Flight

[Smartbear]

Hi, you don't say what the oil level is on the dipstick-is it possible the oil is low enough to temporarily flag up the level light until it's run for a while a splashed around a bit?
Regards

[Flight]

Hi Smartbear. Yes, an omission on my part.
The oil level is on the dipstick top mark.
cheers
Flight

[Mike Fishwick]

The oil level alarm is not detected by a float switch, but uses a small heating element to warm the oil close tothe sensor body. a thermal sensor then detects the warmer oil, until the level falls enough to prevent the warmer oil from reaching the sensor.

These sensors often fail, and give spurious alarms - just more junk which is not needed - except on the later models where the dipstick has been eliminated in the interests of 'progress.'

If you did not have a dipstick you would probably have added oil until it was being pushed out of the cam cover!

[Flight]

Thank for that Mike.
As the light only shows for a few seconds, and from what you say, is not detrimental, I will leave well alone for the time being. If it becomes a nuisance I will look at replacing or repairing.
Many thanks again
Flight

[motco]

My flashing yellow oil light that operates after engine stop illuminates when the level is midway between full and low. It's irritating and sometimes alarming although the oil level is fine.

[pingu]

My flashing yellow oil light that operates after engine stop illuminates when the level is midway between full and low. It's irritating and sometimes alarming although the oil level is fine.

This happened to me last week on the 330. It took less than 0.5l to bring the level back to full.

[Mike Fishwick]

I wonder if the later dipstick-less engines still have the dipstick hole, but blanked off? As BMW dealers prefer top suck the sump contents out - instead of doing it the proper way - there must be a suitable place to insert the suction tube.

A retrofit dipstick would be very handy for owners of the later cars, particualrly those which burn lots of oil, as a means of checking the sensor.

[Brian4]

Hi Mike looking at the Realoem diagrams of the latest engines there douesn't seem to be provision for dipstick at all. I also didn't realise that they don't have individual Main bearing caps but rather all 5 are in a separate casting. Must be to do with speed of assembly.

The consensus of opinion on lack of dipsticks is that most owners of cars do not weekly check oil and wait to be told there is a problem.

My E61 530d didn't have a temperature gauge just a warning if if overheated which was no good as the thermostats used to fail causing the engine to rum cool and poor fuel economy and the dpf wouldn't regenerate and a £1000 bill when it clogged. At least the new one has a temp gauge.

Changing oil is quite a challenge now on modern cars with full undertrays as you have to remove it to get at the sump, a real pain on my daughters TT so close to the ground at least most BMW's have a small cover near the drain plug.

PS the oil level sensors are approx £150 from BMW.

[Mike Fishwick]

While the current designs do not have a dipstick provided, my point was that they will have provision for an oil suction pump - which could be used for a dipstick.

Most modern cars are not designed for DIY servicing, or even non-dealer servicing - thank goodness my Z3 will last me for life!