sky jumper

for those that are interested in oil analysis here is the lastest report for my '01 S500.

the engine is wearing well, but I'm not getting the oil life I should, and the FSS seems to be way off. FSS says 7k left on this oil, but the oil report shows that it's ready for a change now with only 6.7k miles on it. the oil is still in service.

Does the S500 have a PCV valve that could be malfuntioning? has anyone else experienced a discrepancy between the FSS and tested oil TBN?

also - I'm a bit of a newbie when in comes to these cars... how do you reset the FSS after a DIY oil change?...

link to report on bobistheoilguy.com...
http://theoildrop.server101.com/foru...e=0#Post818519

The most recent sample is the Mobil 1 0W40 column. the previous sample was Pentosin.

text:
Blackstone comments:
Wear improved some with the shorter oil run so now your engine looks even better than it did last
time. We mentioned that these 5.0L's are nicely wearing types but yours may be the best in Chicago! You
could have easily run this oil more miles and we don't think 7,500 miles would be too many. If you're going
to try much longer than that you may need to find an oil with a higher TBN. It read only 1.6 here, which
shows little active additive remaining. 1.0 is too low for extended use. No harmful contaminants were
found and the slightly low viscosity isn't a problem.

newton22

At the service screen, hold the odometer reset button (R). It will ask for confirmation of resetting it.

Anyone can reset it with the oil overdue. Those things just remind you, not analyze whether the car needs service or not.

sky jumper

thanks.

I thought there was some kind of sensor on these things that measures oil acidity and/or contamination. it so, it apparently isn't working on my car..

newton22

Don't think so. They're just reminders built into the cars. I just reset mine everytime I change my oil.

Skylaw

Actually, they do measure electrical throughput (dielectric) from a sensor to judge the condition of the oil. Sky jumper may be correct about needing a new sensor.

Resetting may not be dirt simple. It can vary by model and year. See https://mbworld.org/forums/showthrea...52#post1895152 and http://www.benzworld.org/forums/w220...ght=FSS+sensor

The latter link has a reference to the following from Practicing Oil Analysis magazine:

DaimlerChrysler Corporation Flexible Service System

"DaimlerChrysler’s version of the oil monitor is called ASSYST in Europe and the Flexible Service System (FSS) in the United States. Like GM’s sensor, the FFS uses a computerized system to track multiple engine operating conditions. From research on oil quality through the span of an engine’s life, Daimler discovered that the breakdown in oil is determined by such factors as driving habits (frequent short trips vs. long trips), driving speed and failure to replenish low oil levels. Therefore, the FSS monitors time between oil changes, vehicle speed, coolant temperature, load signal, engine rpm, engine oil temperature and engine oil level. It uses this information to determine the remaining time and mileage before the next oil change and it displays the information in the vehicle’s instrument cluster.

"In addition, Daimler discovered that oil degradation is correlated directly with its ability to conduct electric current. Therefore, Daimler has fitted V-6 and V-8 engines with a digital oil quality dielectric sensor, that is mounted above the oil pan along with an analog oil level sensor. This sensor measures changes in capacitance, which effectively is a proxy for the amount and type of contaminants and oil degradation products present in the oil. An increase in dielectric constant (less resistance to electrical flow) indicates oil contamination and degradation.

"Daimler-Benz (Mercedes-Benz) has been incorporating the sensor into its vehicles since 1998."

sky jumper

thanks for the info. very interesting.

I'm guessing the FSS does not use the dielectric sensor to compute remaining oil miles. they use the term "digital" to describe its operation, which makes me think it may be a "fail safe" in case the oil is neglected, or there is some unexpectedly high wear not predicted by the computer's oil life algorithm (which appears to be based solely on engine operating parameters, and not on physical measurements of the oil itself). If the sensor was used to compute oil life remaining (at any given moment) I believe it would have to be analog in nature.

Skylaw - what is your take on this?

newton22

So how come anyone can just reset the FSS? Shouldn't it just reset itself after an oil change?

bamberger_1

Newton, in way it does "reset" after the oil change. I tried it. Changed oil w/o resetting and after a short while the "remaining" milage went up significantly. Of corse not the the reset value, since, as Skylaw brilliantly describes, many more parameters are monitored, not just oil related.

sky jumper

well then, that would seem to indicate the FSS does indeed use the dielectric sensor to compute oil miles, since the oil was the only thing you changed (assuming the oil level was the same before & after the change). I would really like to know more about how this system works.

I suppose in my case the oil is still very clean at 6.7k miles as indicated in the report, so the sensor would have nothing to detect -- but the oil's additives are essentially spent, meaning it is time for a change. But it appears the FSS has no way of knowing this until the engine begins to wear more rapidly spitting metal into the oil - which, in my opinion, is too late. Too bad the sensor cannot detect TBN as well. If it could monitor both it would be a very effective oil life indicator.

sky jumper

one more (stupid) question -- these things do have an oil drain plug don't they? don't want to spend another $125 on an oil service, and I don't have a pump.

kenstudios

Take the skid plate off and you will see it. Make sure you replace the washer when changing the oil with the drain plug. Simple DIY.
Skylaw's explanation seems to explain why I get longer change intervals when driving mostly highway miles but shorter when I only do city driving. What am I saying? I changed the oil and reset the FSS back to 10K miles. Drove to Florida, then to OK back to Memphis and to St. Louis. In all I put about 6K miles in three weeks but the FSS did not reflect 6K miles but rather 3K miles. I think the oil was still in good shape.

newton22

In addition to Ken's post, please note the drain is placed horizontally, therefore it would be necessary to "tilt" the car to drain all 8.5 qts. Though not the safest practice, I jack up one side of the car and place my two jackstands under one side. I would suggest you use this method at your discretion. You can also park one side of the car on a curb to tilt it.