gnma

Hello,

I understand how to check the oil using the FSS system, but does that check also monitor the QUALITY of the oil?

I can see FSS detecting a low/high oil QUANTITY and prompting a message, but my concern is what if the oil quality has deteriorated, and fresh oil is needed. Will the car recognize that or is it mileage/date computation only? Thanks!

Barry45RPM

FSS knows how the car has been driven... (RPMs, acceleration, engine loads...etc.), so it uses that info to tell you when to change the oil based on a knowledge base of engine work VS motor oil life. The car is using Mobil 1 which has a longer effective life than the 15,000 miles they brag about. You will be changing it sooner than its lubricating/detergency life expires.

The engine is incapable of actually testing an oil sample for this info.

Diesel Benz

The car should be able to monitor the oil quality too. My understanding is that the US cars are programmed for a fixed mileage and then don't use this reading for oil change decision.

You can find out this if you add a quart oil and find out the FSS reading changing to a higher mileage for the next service (it isn't from the fact that it reads more oil, you can try siphoning some oil and putting the same amount of new oil back).

paulv

gnma,

Here's a slide from a MB training presentation that supports what others have said.

Regards,
paul...

gnma

Tks. everyone. Paulv your .pdf file is extremely useful, input info. of oil temp/level & quality are sent to the eng. control module. Tks!

Bode

For those E-classes fitted with FSS (prior to dropping FSS on the 2006 models and onwards, and return of the manual dip stick!) the oil quality was/is measured via a sensor monitoring the oil's dielectric strength (sensor B40 per Paul V's excellent drawing). As the oil ages and becomes contaminated it becomes more conductive. This increase in conductivity was found to precede any real deterioration of the vital lubricating properties of the oil, so it is a reliable way (with safety factor) of determining the need for an oil change.

Hope this helps with the original question

paulv

Thanks for the compliment, but I didn't originate that drawing. I downloaded this presentation (only posted an edited version of the FSS Plus) from http://www.mercedestechstore.com. Look in the Training Files section as they have many presentations of the different W211 subsystems -- good info.

Regards,
paul...

gnma

Bode, tks. for the technical answer. U said for MY06 they did away with the FSS - the FSS is a fantastic $ generating system. What do these cars use? (And yes, I sure wish my car had a traditional dipstick).

Paulv - http://www.mercedestechstore.com. Tks. for the awesome link!

Diesel Benz

I don't see the point on the FSS comment. In Europe where FSS is fully used, we can run the car a lot longer between services.

I'm pretty sure the current US cars would use the same oil level/quality sensor as European cars with FSS, the flexible service interval has just been programmed off.

gnma

I was referring to Post #6:

<<For those E-classes fitted with FSS (prior to dropping FSS on the 2006 models and onwards, and return of the manual dip stick!)>>

And my statement was basically if FSS is no longer used, what are they using?

And an oil dipstick is IMO an essential tool needed to measure oil levels in every car. U can have all the sensors in the world, nothing beats basic, manual checks. Seems that MB too felt that way by using a dipstick for MY06onwards. Pulling a spark plug is also a great indicator of engine condition.

Diesel Benz

Considering FSS versus something else, the answer should be "nothing else", just perform the service frequently enough for any conditions! Meaning you don't gain from less frequent services if you drive smoothly.

The dipstick is useful but how many actually go and look at the dipstick against how many see a message on the IC (let's count the average, not among forum members here). And the dipstick may go wrong too, not only the sensor, there are mechanical failures and wrong dipsticks installed on MBs. Of course a dipstick should be more reliable than a more complicated and more capable system.

Anyway, now MB does seem to install a dipstick on new cars and the level readings from the IC are removed but you still get the low oil warnings during driving, a bit of combining the best of the two.