Go Back   MBClub UK - Bringing together Mercedes Enthusiasts > Technical > Engine
MBClub supports BEN Official Stickers @mbclubuk


Engine Engine/transmission and other oily matters

Like Tree1Likes
Reply
 
Thread Tools
Old 13-12-2016, 09:45 PM   #1
New Member
 
merovingian's Avatar
 
Join Date: Nov 2016
Location: Mons Belgium
Car: C220 CDI
Posts: 7
Service indicator and how does it work?

Can anyone explain the criteria for my c220 cdi 2005 service indicator?
Just had a reminder to do a service B which i passed by a couple of weeks. I work at home and the car has done maybe 2500 kms in the last year. I usually take my motorhome if I go anywhere distant.

How does the ECU know if a service is due, by time and or mileage obviously, or is it feindishly more clever; or is that entirely reserved for the most recent models?
merovingian is offline   Reply With Quote
Old 13-12-2016, 09:58 PM   #2
Hardcore MB Enthusiast
 
markjay's Avatar
 
Join Date: Jun 2008
Location: London
Car: W204 C180 Executive SE 2013
Posts: 12,937
The relevant input also includes number of engine starts, engine revs and temp, and oil and filter type.

But ultimately the system does not actually check the oil quality as such - it simply makes an a assessment based on usage history.

Last edited by markjay; 13-12-2016 at 10:18 PM.
markjay is offline   Reply With Quote
The Following User Says Thank You to markjay For This Useful Post:
merovingian (13-12-2016)
Sponsored Links
Old 13-12-2016, 10:41 PM   #3
Hardcore MB Enthusiast
 
whitenemesis's Avatar
 
Join Date: May 2007
Car: Lexus RC300h F-Sport 2016
Posts: 11,982
The car checks the oil quality by measuring the conductance. Conductance goes up the more the oil degrades or gets contaminated. This and the above mentioned usage history goes towards determining service intervals. Oh, and by the number of days since the last service.
whitenemesis is offline   Reply With Quote
The Following User Says Thank You to whitenemesis For This Useful Post:
merovingian (13-12-2016)
Old 13-12-2016, 10:51 PM   #4
Hardcore MB Enthusiast
 
Join Date: Mar 2005
Location: Cheshire, UK
Car: C270CDi Estate (2004 facelift model)
Posts: 6,877
Quote:
Originally Posted by merovingian View Post
Can anyone explain the criteria for my c220 cdi 2005 service indicator?
Just had a reminder to do a service B which i passed by a couple of weeks. I work at home and the car has done maybe 2500 kms in the last year. I usually take my motorhome if I go anywhere distant.

How does the ECU know if a service is due, by time and or mileage obviously, or is it feindishly more clever; or is that entirely reserved for the most recent models?
The more recent models are on fixed interval (12 months or 15,500 miles) servicing. MB moved to that around 2007.

Yours could have been set for fixed interval (my dealer kindly offered to do that on mine ) hence it's come up after a year.

As to how the variable bit works, it's been discussed many times and I don't think anyone (outside of Mercedes) really knows. I do about 6000 miles per year, but that's mainly one long round trip per month - day-to-day I don't use the car. For the last few services mine has run to the full 2yrs (which is the maximum).

One thing (for extended interval servicing) is the oil quality has to be set correctly and then you get a 1.3 multiplier on the mileage. So at reset mine shows 13000 miles to service, but whenused for long journeys it counts down 100 miles for every 150 the car does. So the max possible mileage would be 19,500.
Rory is offline   Reply With Quote
The Following User Says Thank You to Rory For This Useful Post:
merovingian (13-12-2016)
Old 13-12-2016, 11:51 PM   #5
New Member
Threadstarter
 
merovingian's Avatar
 
Join Date: Nov 2016
Location: Mons Belgium
Car: C220 CDI
Posts: 7
Interesting and indeed fiendishly clever. I will have a look at the date of the last oil change and based on that draw my conclusions as to wether its simply annual or its due to starts and stops or "conductance" which I can only liken to resistance measured in Ohms
merovingian is offline   Reply With Quote
Old 14-12-2016, 06:28 AM   #6
Hardcore MB Enthusiast
 
markjay's Avatar
 
Join Date: Jun 2008
Location: London
Car: W204 C180 Executive SE 2013
Posts: 12,937
Quote:
Originally Posted by merovingian View Post
Interesting and indeed fiendishly clever. I will have a look at the date of the last oil change and based on that draw my conclusions as to wether its simply annual or its due to starts and stops or "conductance" which I can only liken to resistance measured in Ohms
1. Some models are fitted with 'oil quality sensor' which measures conductivity.

2. Up to MY 2007, the service interval was flexible, and on low annual mileage cars you can expect to see service intervals of between 15 and 24 months. From MY 2007 onwards, the service interval is fixed at 12 months (unless required earlier due to annual mileage)
markjay is offline   Reply With Quote
Old 14-12-2016, 08:03 AM   #7
Hardcore MB Enthusiast
 
Join Date: Jul 2016
Location: Garden of England
Car: E350 CDI W212
Posts: 197
My service indicator has gone from service in 11500 miles to service in 190 days B7

Why the change?

Thanks
such01 is offline   Reply With Quote
Old 14-12-2016, 08:44 AM   #8
Hardcore MB Enthusiast
 
Bobby Dazzler's Avatar
 
Join Date: Jan 2005
Location: Mittel England
Car: ( )
Posts: 12,593
Quote:
Originally Posted by such01 View Post
My service indicator has gone from service in 11500 miles to service in 190 days B7

Why the change?

Thanks
Are you doing very low mileage?

With 11500 miles to go in the next 6 months, compared to say 2500 miles in the last 6 months, perhaps the car decided you'll be limited by time and not mileage, so days will be a better indicator for you. Just a guess mind.
Bobby Dazzler is offline   Reply With Quote
Old 14-12-2016, 09:45 AM   #9
Hardcore MB Enthusiast
 
markjay's Avatar
 
Join Date: Jun 2008
Location: London
Car: W204 C180 Executive SE 2013
Posts: 12,937
Quote:
Originally Posted by Bobby Dazzler View Post

Are you doing very low mileage?

With 11500 miles to go in the next 6 months, compared to say 2500 miles in the last 6 months, perhaps the car decided you'll be limited by time and not mileage, so days will be a better indicator for you. Just a guess mind.
This is correct. When the mileage between services is very low, the car switches from mileage-based service interval to time-based service interval.
markjay is offline   Reply With Quote
Old 14-12-2016, 10:49 AM   #10
Hardcore MB Enthusiast
 
Join Date: Nov 2003
Posts: 407
Quote:
Originally Posted by markjay View Post
1. Some models are fitted with 'oil quality sensor' which measures conductivity.
I'd be surprised if it measures conductivity. Our tests showed that to be a rubbish way of doing it. You are better off measuring the dielectric properties but even then you need to start with a very well behaved oil that is well characterised. Normally this means buying a special oil from the manufacturers.
I havn't looked at it for a while so I'd be interested if anybody has any newer information on oil quality sensing and if its actually done in any meaningful way.
My rather cynical view is that when this was being pushed the conclusion people came to was that in most cases oil was lasting longer than they expected, resulting in less visits to the service centre, with a resulting loss of revenue. Things then switched back to a time based limit which conveniently is now annual. I don't believe there is any evidence to say that oil wears out after a year if you do low mileage! Thus I conclude there is a commercial imperative at work here.
DrNick is offline   Reply With Quote
Old 14-12-2016, 11:10 AM   #11
Hardcore MB Enthusiast
 
Join Date: Nov 2005
Car: MB
Posts: 3,976
Don't they simply alert every one or two years or at a set mileage whichever comes first?
DrFeelgood is online now   Reply With Quote
Old 14-12-2016, 11:32 AM   #12
Hardcore MB Enthusiast
 
whitenemesis's Avatar
 
Join Date: May 2007
Car: Lexus RC300h F-Sport 2016
Posts: 11,982
Certainly the 219 from 2005 measures oil conductance, as documented in WIS. I'm sure other models do to. One can extend the service interval significantly just by topping up with fresh oil.

As has already been stated current trend is pure time based intervals.
whitenemesis is offline   Reply With Quote
Old 14-12-2016, 11:35 AM   #13
Hardcore MB Enthusiast
 
Join Date: Nov 2003
Posts: 407
Quote:
Originally Posted by lewyboy View Post
Don't they simply alert every one or two years or at a set mileage whichever comes first?
This is the traditional way of doing it.
However, two minutes thought will tell you that its rather arbitrary. So engineers decided to try and actually measure when the oil needs changing. After all, you wouldn't consider changing other things like brake pads on an arbitrary whim such as every year! No, you'd try to figure out a way of telling you when they need changing, such as a pad wear sensor.
It turns out that oil is a tricky thing to measure the quality of as there are so many variables.
It also turns out that oil quality has improved tremendously over the last few years as research has progressed into what it actually does, as has the tolerance of engine manufacture. This has resulted in oils overperforming, and so a normal service life can be pushed out a long way. Bizarrely this has made the need for a quality sensor actually more important to catch the outlier cases, and to help you wring the maximum life out of the oil.
This is fine for commercial vehicles/ships etc where downtime is expensive, and an oil change can use 100s of litres of oil. Sensors exist for these situations though.
Cars are different. They don't normally have a life anywhere near a commercial vehicle so in 95% of cases oil quality isn't going to be the limiting factor. This makes it more of a marketing issue. If you offer a super high tech variable service interval, you can use that to sell more cars.
However, you then sell less oil at services because there are less services if it works properly. Thus there would appear to be a compromise whereby you offer some form of high techery but hobble it so the cars still come back for near annual services.
Companies seem to have got bored with that so have now moved back in general to annual services (Oil is only one thing that needs maintenance after all!) with the option to either buy a discounted service plan, or by buying several years servicing in advance to keep you coming back
DrNick is offline   Reply With Quote
Old 14-12-2016, 01:17 PM   #14
Hardcore MB Enthusiast
 
markjay's Avatar
 
Join Date: Jun 2008
Location: London
Car: W204 C180 Executive SE 2013
Posts: 12,937
Quote:
Originally Posted by DrNick View Post

I'd be surprised if it measures conductivity. Our tests showed that to be a rubbish way of doing it. You are better off measuring the dielectric properties but even then you need to start with a very well behaved oil that is well characterised. Normally this means buying a special oil from the manufacturers.
I havn't looked at it for a while so I'd be interested if anybody has any newer information on oil quality sensing and if its actually done in any meaningful way.
My rather cynical view is that when this was being pushed the conclusion people came to was that in most cases oil was lasting longer than they expected, resulting in less visits to the service centre, with a resulting loss of revenue. Things then switched back to a time based limit which conveniently is now annual. I don't believe there is any evidence to say that oil wears out after a year if you do low mileage! Thus I conclude there is a commercial imperative at work here.
1. According to MB, the oil quality sensor measured electrical conductivity of the oil inside the sensor's chamber. However, not all models are fitted with this sensor, and MB do not say if the oil quality sensor is one of the input factors for the flexible servicing regime. It is not impossible that it simply alerts the driver when the oil has too much water in it - or ferrous particles - I don't know.

2. The reason that MB switched to fixed annual service in 2007 was to make their vehicles more attractive to fleet managers. When the flexible servicing regime was first introduced it was thought that the reduced overall cost would appeal to fleet managers, but this turned out not to be the case - fleet operators were more concerned about the inability to predict, schedule, and manage service schedules. This is again officially according to MB - whether there were more sinister intentions behind this, I do not know.

Last edited by markjay; 14-12-2016 at 01:22 PM.
markjay is offline   Reply With Quote
Old 14-12-2016, 02:14 PM   #15
Hardcore MB Enthusiast
 
Join Date: Nov 2003
Posts: 407
There seems to be conflicting opinion

Mr Whitenemesis in the past has quoted the WIS which says it uses capacitance


Extract from WIS doc #gf1840p411102am

"The oil sensor operates in accordance with the capacitive
measuring principle and features integrated electronics which
analyze the three signals (oil level, temperature and quality).

Oil level and oil quality are detected on the basis of the capacitance of the engine oil (dielectric).
The capacitance of the engine oil is as much as 6 times greater if the oil quality is poor."

Maybe they have used more than 1 type of sensor. It seems to have started a heated forum discussion in the past!
DrNick is offline   Reply With Quote
Reply

Tags
indicator, service, work


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools



All times are GMT +1. The time now is 07:07 PM.


MB club UK is A Mercedes Enthusiast club run by enthusiasts for enthusiasts, MBClub UK is in no way affiliated with Mercedes-Benz, DaimlerChrysler or any of their respective trademarks. The posted views of our members are in no way the views of MBClub.co.uk or its owners.
Find us on Google+