[Jon D]

Something very strange has happened to my F10 535d - the engine oil level is slowly increasing. Since new I have checked it on, at least, a weekly basis and always in my garage, which has a perfectly level floor.
For the first 11k miles it showed no drop and was always right on the top notch of the dipstick, confirmed by the on-board display, but I now see that it has risen by about 1/8" over the top notch and the display is showing a yellow over-full warning.
There is no visible damage underneath the car to indicate a dented sump, so I'm wondering if the N57 diesel engine has an oil/fuel heat exchanger which might be leaking internally.
I'll contact my dealer in the morning, but I'm hoping someone might have an idea or two in the meantime.
Any thoughts welcome - thanks.

[EdM5]

Very strange indeed. I'm curious what the dealer will tell you.
I've noticed the yellow over-full warning a few times on my 535d as well (at about 20.000 kms), but I didn't inspect the dipstick when it happened.

[Jon D]

Originally Posted by EdwinF10

Very strange indeed. I'm curious what the dealer will tell you.
I've noticed the yellow over-full warning a few times on my 535d as well (at about 20.000 kms), but I didn't inspect the dipstick when it happened.

As was the case with my previous car, an E92 330d, the F10's indicated oil level is particularly sensitive to the slightest change in attitude. Therefore, I would strongly recommend that you closely monitor the dip-stick over a period of regular usage, whilst ensuring that the car is on a perfectly level surface. You may end up being equally concerned as I am.
Apart from mechanical damage to the sump causing an erroneous reading, the only other answer I can think of is that fuel could be leaking into the oil system, hence my query about an oil/fuel heat exchanger, but, as I said, I don't know if the N57 has such a device.
I also posted this question on the UK 3 series sub forum which has a considerably large and very knowledgeable membership and one of the respondents suggested that it might be a DPF problem. However, I can't see how any fuel that is unburnt during the regeneration cycle could find its way into the oil sump.
I'll keep you posted.

[Jon D]

Originally Posted by EdwinF10

Very strange indeed. I'm curious what the dealer will tell you.
I've noticed the yellow over-full warning a few times on my 535d as well (at about 20.000 kms), but I didn't inspect the dipstick when it happened.

Edwin,
I've just received another response over on the UK forum from someone I consider to be particularly well informed. He raises the possibility of HP fuel pump seal or injector issues which I hadn't thought of, either of which could increase the oil level by fuel dilution and both with potentially serious consequences, so I reiterate my suggestion to closely monitor your oil level. Check comments here: http://www.e90post.com/forums/showthread.php?t=598798

[1HOT BMR]

It is so nice that you have a dipstick to confirm this. It would be really unnerving to see the oil level rising and turning yellow on your e-gauge and no way to verify if it's the gauge or one of the other scenarios mentioned here. Consider yourself very lucky . . . what would I give for a dipstick . .

[EdM5]

Thanks Jon, that's some very good advice. Much appreciated!

[Jon D]

Originally Posted by EdwinF10

Thanks Jon, that's some very good advice. Much appreciated!

You're welcome Edwin, my car goes into the dealer tomorrow morning and I'll let you know what they find.

[Gran Turismo]

Jon, are you by any chance driving many shorter trips and thus cancelling the DPF regeneration procedure from time to time?

I've just stumbled across some German posts and articles about increasing oil levels in Diesel engines related to the cleaning / regeneration of the DPF in the context of short trips.

A contamination of engine oil with diesel up to 10% is apparently not considered as critical, however the general recommendation for such cases is to change the engine oil twice as often than the standard requirement.

[Jon D]

Originally Posted by Gran Turismo

Jon, are you by any chance driving many shorter trips and thus cancelling the DPF regeneration procedure from time to time?

I've just stumbled across some German posts and articles about increasing oil levels in Diesel engines related to the cleaning / regeneration of the DPF in the context of short trips.

A contamination of engine oil with diesel up to 10% is apparently not considered as critical, however the general recommendation for such cases is to change the engine oil twice as often than the standard requirement.

Thanks GT, as it happens in last 2 or 3 weeks and approx 150 miles I haven't made a journey of more that 10 miles and I have also heard others suggesting this might be a DPF regeneration issue.
However, I simply cant see how any fuel, unburnt in an incomplete DPF cycle, could find it's way into the oil sump. As I understand it the extra injector is mounted directly in the exhaust system and, therefore, entirely unrelated to the oil system.
If you could post any links you have about this I'd be very grateful - many thanks.

[Gran Turismo]

Originally Posted by Jon D

If you could post any links you have about this I'd be very grateful - many thanks.

This is probably a good starting point: http://www.adac.de/infotestrat/repar...g/default.aspx

Also google for "Ölverdünnung" and "diesel", or in English for the terms oil dilution and DPF

According to the ADAC article above, the extra "cleaning" fuel is injected into the cylinders after the top dead centre, doesn't always get completely burnt and thus gradually finds its way into the oil via the cylinder walls...

[Jon D]

Originally Posted by Gran Turismo

According to the ADAC article above, the extra "cleaning" fuel is injected into the cylinders after the top dead centre, doesn't always get completely burnt and thus gradually finds its way into the oil via the cylinder walls...

Thanks again GT. I had mistakenly understood that the fuel required to recycle the DPF, was managed by a separate injector/ignition system and not as described above. It all makes perfect sense now and, considering that I have made a series of short trips recently, that's probably the problem.
I'll still take the car into the dealer tomorrow as scheduled and if they find nothing wrong, I'll have to do an oil change to get rid of the fuel contamination.
I guess I'll also have to do longer runs more frequently, whether required or not and thereby wasting fuel, which makes a bit of a mockery out of diesels being more economical.
I did a 'google' search as you suggested and, for anyone interested, I found a very detailed description of DPF systems here: http://www.jaguarforum.co.uk/viewtopic.php?f=22&t=25040

[Jon D]

Result.
The dealer's just called to say they've found a fault with the oil level sensor and that they'll replace it under warranty.
I must say that I'm relieved to know it wasn't the recent brief spell of short journeys that was causing the problem.
As to the perceived slight increase on the dip-stick - I guess if you look hard enough for something you'll find it and the 'yellow' overfull warning was obviously the trigger.
My sincere thanks to all respondents for your help and interest.

[EdM5]

Thanks for sharing.
I'll have that checked as well.

In a car full of sensors, cpu's and electronics, nothing beats the good old dipstick

[Needsdecaf]