JosanK

Have only been able to drive a few thousand miles a year on my SL55 (travel and whantnot ). Had oil changed September 03. I change at least every 5000 miles. Not sure if I'll be at 5K mark by 9-2004. Mechanics have always told me to ALWAYS change oil at least once a year (synthetic or not) due to combustion byproducts in oil. Not time for service A so I guess I'll find an independent to do it. Any comments on oil change intervals on low mileage cars?

By the way, when I changed the oil last September I had 4200 miles on the car. The FSS didn't revise the miles to next service interval, not by a single mile.

blueSL

My SL55 is coming up to 2 years old in September and the car is still saying it doesn't need a service A for another 5k miles or so. The car has an oil quality sensor which looks at its opacity so that contamination with combustion products, water or ground up engine will show up as deteriorating oil quality.

Change the oil once a year if it makes you feel better; I'm happy to be guided by the service interval indicator. Changing the oil will not, by itself, change the indicated time/distance to the next service. It is reset when the service is done and the car then starts a learning process based on usage (cold starts, distance, oil condition) to figure out when the next one should be.

Wolfman

I agree with BlueSL...

There really is no need to change the oil unless indicated by the system. I have about 18000 miles on the car and looked at the oil as it was changed during the small service interval (around 12000 miles). It was in excellent shape...

Wolfman

theboogers

change to oil often if you are going to keep the car. i change every 5k and do not care what the computer says. fluids are the most important part of the car.

blueSL

As I said, if it makes you feel better, do it. But don't skimp on oil quality and replace the filter as well. Far better to use the best synthetic for longer than a few quarts of Jiffy-Lube's finest for a few months.

shoes

I am wondering what Mercedes will recommend for oil changes after the free maintenance goes away in 2005?

JosanK

I wouldn't trust the FSS. I don't believe that sensors of sufficient quality to determine all the variables in oil are in these cars. Remember, I changed the oil at 4200 miles AND FSS DIDN'T CHANGE AT ALL, IT STILL SHOWED 6K TO SERVICE. Think about that. If the FSS sensors are that good it should have gone from 6k remaining to 10K remaining, or at least 8k. It didn't. Didn't change at all.

If you really want to test this, get the oil analyzed. I have. It is definitely going downhill by 5K (mainly in upper level effective viscosity). If you talk to the actual mechanincs, not the service advisors, or any independent mechanic, or race shop, or commercial operator, they pretty much all say the same thing which is "If this was my my car no way would I go 10K between changes". Listen to people who rebuild and/or modify engines gor a living. They see what's going on inside.

This whoile 10K/FSS mantra is some kind of marketing/political thing. It seems to be a message of "look at our low maintenance, we're so maintenance free". The agenda of Mercedes is NOT for the long life of your engine, just long enough to get through warranty. If you intend to keep the car a while change oil more frequently than 10K. Is it worth saving $150 now and then on a $120K+ vehicle?

Wolfman

I don't know of all criteria used by the computer, but oil is just one of them. Or maybe I just don't take it too seriously; I have mostly driven MB's big V8's and quite frankly, even the "old technology" (1980+) engines never needed oil replaced every 4-5K miles. Minimum were 10,000 kilometer (about 6.2k miles) service intervals and in Germany I pushed these cars always from 125 mph to speed limit .
Coincidently all engines had no issue making it to 200k miles

I would be more concerned about high-revving small engines and transmission fluid...

Wolfman

blueSL

The service interval is based not just on oil quality but other usage statistics, such as the number of cold starts; remember that the majority of engine wear occurs in the first 30 seconds after starting until the oil is circulating. The life of your engine will depend much more on how you use the engine before it reaches operating temperature than it will on replacing perfectly good oil ahead of time.

The service indicator is reset by the dealer when a service is done. The sensor does not suddenly say, hey guys, new oil, reset the service interval!

Modern lubricants are so good that you just don't need to worry. Spend time instead checking your tyre pressures every couple of weeks.

JosanK

You can reset the service indicator yourself. It's documented in the manual.

Does anyone on this forum know exactly how this FSS thing works? I mean, details. A friend of mine who works on desgining sensor arrays for turbine engines calls the Benz (and the BMW) FSS technology "a K-Mart level blinking light".

Like I said, I had the oil from the first change ANALYZED. I used to own a plane. Got in the habit of doing this. Even though the oil looked ok it was NOT offering the same lubricating properties as when it was new. It would be seriously degraded by 10K. I tend to push this car hard, lots of near redline shifts. I want good fluids.

The dealer (service advisor) predicted that when I changed oil at 4200 that the service indicator would adjust. It didn't. Not by one mile. Yet the engine oil analysis showed the oil had definitely changed properties. How good are the FSS sensors if it couldn't detect this? Is this thing little more than an "idiot light" with numbers?

This incident has made me less than comfortable with the knowledge the service advisors have.

Again, I repeat, the mechanics who actually work on the car STRONGLY advise changes before 10K. This includes a "master mechanic" from the dealership. This was told to me during a test ride for problem diagnosis. The mechanic told me that they had been instructed not to contradict the Benz "party line", but he was willing to discuss this away from prying ears. Quote "If this was my car no way I would go over 5K". Since he actually works on these engines for his rice bowl I paid attention to this.

As far as the comment about oil changes on the old V8's, those older cars were so anemic that they didn't give the oil much of a workout. A supercharged 8 has charecteristics more like a motorcycle. It is much harder on the oil.

If you really want to verify this just have your oil analyzed on the next change.

Concerning tires, I've verified the pressure readings that the sensors give against an accurate gauge. They can be trusted. I check the readout daily.

blueSL

What is also the case is that mechanics here are encouraged (and incentivised) to prey on customers' anxieties to drum up extra business by telling them what they want to hear. "Do I need to change the oil once a week?" "Well, not strictly, but if this beautiful (you have made such a good choice Mr Customer) car were mine, I would". And you believe him because he's got some fancy framed plaque on the wall saying he's been on a course. That'll be $200 (wasted) dollars, thank you. In the total scheme of things, though, it's nothing compared to how much your car is depreciating or costing you each month.

I have long since giving up believing anything a Service Advisor tells me, other than when they can work on my car and telling you the service interval indicator would increase just because the oil had been changed was wrong. That counter has 100 clicks, starting at 10000 miles. Each time the car thinks it's covered 1% of the service interval, the "miles to service" clicks down 100 miles, irrespective of the actual miles covered and nothing, other than a reset (there are separate user and dealer resets) will cause it to go back up.

Currently, in my car, the total of miles covered and miles to go is 10800 miles. I think there's also a time element which will eventually kick in, but my car is now 21 months old and there's no sign of that yet.

A good measure of oil condition is its opacity and viscosity. As oil ages, both will increase. Sure, there are other characteristics of the oil which are ageing at the same time but you do not need to do a full analysis of the oil to form an opinion of its condition, all you need is a diagnostic indicator and oil which is getting cloudy or sticky due to water absorption or other contaminents is due for replacement.

It's just like taking someone's temperature and blood pressure gives a reliable indicator of their overall health.

You're obviously wedded to the idea of changing your oil more frequently and your dealer/oil company will love you for it. Me, I can sleep easy at night knowing that the car will ask for service when it needs it.

pablo4.2

I'm with KosanK. If those sensors were accurate they would have to reset to some degree. They are glorified idiot lights. I would change the oil more often than routine MB service. With a supercharged engine, certainly more than once a year or 10,000 miles if driven hard.

Wolfman

I agree with BlueSL but it really doesn't matter; do what you feel comfortable with. Everyone has their own comfort zone and should do what they feel is appropriate, that is with the exception of brakes and tires which are essential to safe driving.

Regarding driving the car hard, unless you are tracking it I can't really see where you could push the car really hard in the US (taking it up to 155 mph for a few minutes shure doesn't give the car any workout).

Wolfman

JosanK

I don't want a flame war on this. But I feel compelled to make some points.

All of the people who have advised me on more frequent oil changes actually repair, design or modify engines. All of them. They don't personally stand to make any money off of me. Why would they lie? They folllow their advice with their own vehicles (which includes Ferrari's, modified engines, racing bikes, classic muscle cars, Rolls Royces, etc). I am giving high credibility to advice from these people because this is what they do, all day, every day. They see a lot of engines. They see examples of use and wear all the time.

pablo4.2 said "If those sensors were accurate they would have to reset to some degree. They are glorified idiot lights." Yes. Word.

Concerning the statement "Regarding driving the car hard, unless you are tracking it I can't really see where you could push the car really hard in the US". Idling in rush hour traffic on a 106 degree day can do quite a number on your oil.

Concerning the statement that "It's just like taking someone's temperature and blood pressure gives a reliable indicator of their overall health." Not true if you have HIV or HEP-C in your blood or if you have early cancer. Temerature and blood pressure are very gross level tests. A person that's good on these in January can be in a world of hurt by December, which is kind of my point on oil.

blueSL

Now I think you've really lost the plot. The operating temperature of the engine hardly changes as the ambient changes. That's what the termostats are for. I'm an engineer as well, and my message to you is, forget it. In normal everyday driving, you are simply not going to stretch the engine far enough to make any impact at all.

pablo4.2

In very heavy traffic the engine is being used under extreme conditions by any manufacturers standards. On this there is no valid argument. In the summer with intense heat this situation worsens. Under normal driving, the ambient temperature makes no difference but that was not the point that JosanK made.

blueSL

The main purpose of oil is to lubricate surfaces move against each other and also to provide an additional route for cooling when the oil is itself separately cooled. Friction, and therefore wear, increases with the N'th power (up to 6) of the relative velocity of the two surfaces, and wear will be at its greatest when the oil is cold and viscous and therefore not doing its job and also when the engine speed is high. That's why you should not race a cold engine. Once the temperature is up to normal, idling in traffic is not a problem and Death Valley provides rather greater cooling challenges during testing than 106F. If anything, idling when the engine is cold while you defrost the windshield in winter will do more harm. Better to start the engine and drive off immediately.

pablo4.2

Idling and driving in heavy traffic are not the same thing. Driving in heavy traffic is considered an extreme driving condition by ALL auto manufacturers regardless of what you say and believe.

Wolfman

Coming back to the original post, JosanK believes that it's good idea to change oil more often than Mercedes recommends.

It certainly doesn't hurt, maybe except the wallet, but it simply does not appear to benefit either, at least not in a statistically tangible way.

While Mercedes has been blamed for many shortfalls in quality, engine damages due to contaminents or short engine life is not one of them.
In fact, Mercedes has probably the best track record on engine durability in the industry...

Btw, idling in traffic (heavy or at 106F) will certainly not stress a super-charged engine. It simply doesn't engage

Wolfman

pablo4.2

Heavy traffic stresses ANY engine.

Deception

As long as you are using a premium quality synthetic oil in your engine, you will have no issues whatsoever following Mercedes' FSS intervals. A few years ago, MB had some problems with customers following FSS intervals using conventional dino oil, but they have smartened up and sent out numerous TSBs and letters to customers reminding them that synthetic is the only oil that can be used if they wish to follow the FSS "long drain" intervals.

JosanK

FYI -- description of FSS from www.practicingoilanalysis.com


"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 FSS 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. "

The dielectric constant test showed no difference between new oil and oil with 4300 miles on it, but Titan oil analysis showed definite wear in the one year old oil. The FSS is a very simple system, barely more than a spreadsheet with table lookup and a toy sensor.

Wolfman

Seems to be working fine for a few million engines so far

Kidding aside; thanks for the info, the FSS details were very informative...

Wolfman