Service interval countdown

S

samZ4M

Active member
 Oxford
I've noticed the interval for the next service has dropped down quite quickly, so I kept tabs on it for a bit. My drive to and from work is 13 miles each way, but every time I start the car, 25 miles have been knocked off the mileage left.

So the 10k that is says, really is going to be 5k...

Surely this can't be right.
 
Goes off oil condition and I think it factors in fuel consumption too, if you do an interim oil change that should give you a bit more time. At the moment I'm having an inspection carried out every 2 years but oil changes every 6 months or 7.5k.
 
I'm pretty sure I'm right in saying it has nothing to do with oil 'condition', the car has no way of monitoring this. It is purely down to fuel consumption. Doing an interim oil change will not affect the mileage countdown but is advisable.
 
Could lots of short journeys speed up the time between indicated services? Engine only just up to temperature before being shut down = more potential wear, so the ECU suggests more regular oil changes?
 
It's only 13 miles, but takes at least 30 minutes, usually closer to 50.

mpg is low due to traffic (and the noise of the thing at 7k!)
 
JAD said:
Could lots of short journeys speed up the time between indicated services? Engine only just up to temperature before being shut down = more potential wear, so the ECU suggests more regular oil changes?
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Nope, just that short journeys increase the mpg as the fueling at cold start is very rich.
 
TomK said:
JAD said:
Could lots of short journeys speed up the time between indicated services? Engine only just up to temperature before being shut down = more potential wear, so the ECU suggests more regular oil changes?
Click to expand...

Nope, just that short journeys increase the mpg as the fueling at cold start is very rich.
Click to expand...

Presume that's "decreases", so more fuel used = shorter oil change/service intervals.
 
Does the M have the same oil level sensor as the N series engines, despite having a dipstick? The N52 definitely measures oil condition. If not then I can only think that it's on fuel usage.
 
From what I can see on RealOEM the same oil level sensor is used in the N52 and S54; in which case the oil quality is monitored, sends the signal to the DME which calculates when the next service is due.
 
I'm confused. How does the oil level sensor measure the 'quality' of the oil?
 
It really seems to go down 25 miles every time I move it.

From car park to petrol station, all of 200 yards, 25 miles came off!
 
yep that sounds about right! No chance of getting 15000 miles out of the on board computer unless you drive down motorways like a granny all the time. I usually find 15k interval equates to around 10k in my real life.
It's purely a fuel economy thing so you will find your usage profile will hit it hard.
 
TomK said:
I'm confused. How does the oil level sensor measure the 'quality' of the oil?
Click to expand...

This is from the New Generation 6-Cylinder N52 manual and only applies if the sensor is actually present in the S54 - looks like it is from RealOEM but I can't be sure and could well be wrong.

Electronic Oil Condition Monitoring
There is no dipstick including the guide tube on the N52 engine. This represents a
convenience function for the customer while enabling more accurate recording of the
engine oil level.
The engine oil level is measured by an oil condition sensor (OZS) and indicated in the
central information display (CID). The engine oil temperature and the oil condition are
also registered or calculated by the oil condition sensor. The signal from the oil condition
sensor is evaluated in the ECM. The evaluated signal is then routed via the PT-CAN,
SGM and the K-CAN to the instrument cluster and to the CID.
Registering the engine oil level in this way ensures the engine oil level in the engine does
not reach critically low levels thus protecting the engine from the associated damage. By
registering the oil condition, it is also possible to determine when the next engine oil
change is due. Over filling the engine with oil can cause leaks - a corresponding warning
is therefore given.
Function of the Oil Condition Sensor
The sensor consists of two cylindrical capacitors arranged one above the other. The oil
condition is determined by the lower, smaller capacitor (6). Two metal tubes (2 + 3),
arranged one in the other, serve as the capacitor electrodes. The dielectric is the engine
oil (4) between the electrodes. The electrical property of the engine oil changes as the
wear or ageing increases and the fuel additives break down.
The capacitance of the capacitor (oil condition sensor) changes in line with the change in
the electrical material properties of the engine oil (dielectric). This means that this capacitance
value is processed in the evaluation electronics (7) integrated in the sensor to form
a digital signal.
The digital sensor signal is transferred to the DME as an indication of the status of the
engine oil. This actual value is used in the DME to calculate the next oil change service
due.
The engine oil level is determined in the upper part of the sensor (5). This part of the
sensor is located at the same level as the oil in the oil pan. As the oil level drops (dielectric),
the capacitance of the capacitor changes accordingly. The electronic circuitry in the
sensor processes this capacitance value to form a digital signal and transfers the signal to
the DME.
A platinum temperature sensor (9) is installed at the base of the oil condition sensor for
the purpose of measuring the engine oil temperature.
The engine oil level, engine oil temperature and engine oil condition are registered
continuously as long as voltage is applied at terminal 15. The oil condition sensor is
powered via terminal 87.
 
TomK said:
yep that sounds about right! No chance of getting 15000 miles out of the on board computer unless you drive down motorways like a granny all the time. I usually find 15k interval equates to around 10k in my real life.
It's purely a fuel economy thing so you will find your usage profile will hit it hard.
Click to expand...
Mine's about 14k between services (excluding interim ones) - but as you say, most of my driving is motorway, with the odd ring trip & track day.
 
TomK said:
I'm pretty sure the S54 doesn't have this functionality, but I stand to be corrected.
Click to expand...

As am I :) I was pretty amazed when I found out the N52 actually measured the condition, also assumed it would just be on fuel consumption.

Anyone willing to pop their VIN into RealOEM and see what part number the oil level sensor is (if it's even present)?
 
Interesting write up:)
I always do oil change on my cars v v regularly
Mazzer oil/filter every 1k
M has had 2 oil/filters and then another with inspec2 I had v early at 10k as was £429 at main dealer!
So that's 3 in a year and 4 months and 9k

Call me fussy:)
 
yeah you're fussy I guess, doesn't really help answer the question.
Oil sensor part numbers for z4m are
7567723
7540351
7607910
All appear to be the same part over different years. How does that compare to the N52 steve?
 
Wow that's the first I've heard of oil condition sensing! Very cool! My guess is that they worked out a way to use the standard capacitive style sensor normally used to sense the oil level as a condition sensor also. It would be fancy software in the ECU that figures it out though so I doubt the S54 would do it.
 
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