I'll toss this out for discussion.

This is a used oil analysis from a 2002 MBenz 3.2L V6 gas engine. The oil is the factory-recommended Mobil 1 0W-40.

This oil has covered about 10,200 miles. The car had 55,000 miles when this sample was pulled. The FSS suggested the car could have traveled another 5,700 miles before this B Service was due.






Background: We bought this car June '05. It had been sitting on the dealer's lot since 10/04. The car had been fully serviced by MBz in 9/04. I know the dealer would have started this car and left it idling for extended periods during the time they owned the car and would have been forced to shuffle it around for major snow removal we encounted last winter. When I changed the oil earlier this month I did note white build up on the underside of the oil cap.


This car has consumed NO measurable amount of oil over the past 10k miles. The car runs extremely well, fuel economy is somewhat better than I would have expected and the car has an excellent service history.

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Cars that sit in dealer inventory lead tough lives. Frequent starts and short running time can cause crankcase fuel dilution, and since the typical 90 percent distillation curve of gasolines is about 300F, once these heavy, high boiling point components mix with the oil, they will stay until the oil is drained.

Suggest you run an analysis of the new oil when you change it or before. Assuming you are driving the car "normally" i.e. trips of sufficient length to fully warm up the engine - including the oil, not just the coolant, you should see much lower fuel dilution.

If you've accumulated over 10K miles in six months I suspect your average trip length is above the average for most cars.

Duke

Yeah, that's the strange part about it - - the car is NOT used for short trips. it's quite common for her to do 80 miles/day during the week. I suspect this fuel dilution occured last winter at the selling dealership.

I will likely do a 5k mile sample and see if it's under control. I thought the rest of the values looked reasonable per mileage traveled.

Thanks for your comments.

Any thoughts on why the copper is elevated compared to the other traditional wear metals (absence of Tin and Lead) ?


thanks.

Most modern bearing materials use copper or aluminum as base materials. Tin and lead were the primary components of ancient, soft babbit bearings, but they disappeared by the fifties.

Babbit was a good bearing material in the era before full flow oil filters because it has good "embeddability" and particles would embed in the bearing material rather than gouge the journal, but babbit lacks load capacity and fatigue life.

Modern bearing materials have much higher load capacity and fatigue life, but poor embeddability, which is not that important with good filtration. Modern main bearings with OE specified maintenance will usually last over 300K miles and very few modern engines will ever need bottom end overhauls. The cars will end up in junkyards for other reasons before the bottom end wears out.

From your oil analysis it looks like Mercedes uses copper alloy bearings, but I don't think 24 PPM means that there's any problem with them.

Duke

OK, thanks for the explanation. I just thought it a bit odd that the Cu popped up like that.

I'll re-sample at 5k miles and hope that gasoline dilution disappears.


Happy New Year.

Subject car: 2002 MBenz E320 with ~67k miles.

Car has covered nearly 12k miles on this oil change. FSS system suggested car could have traveled another 800 miles prior to changing oil.


Oil was noticeably darkened at this changeout compared to previous 10k mile interval. Oil had slight odor to it. Not top off oil added over this 12k mile interval.




Comments:


No corrective action required. Oil is suitable for continued use. Resample at next regular interval.



- - OAI


Oil and filter changed. ELF Full-Tech 0W30 (229.5 spec product) used and will be sampled at next change interval.



Starting viscosity for M1 0W-40 is

cSt @ 100º C 14.3

Complete spec sheet for M1

I think this new analysis supports a conclusion that the fuel dilution happened on the dealer lot as I previously opined.

Darkening is usually due to oxidation, which is probably why the oil monitor suggested only a few hundred more miles.

I believe the oil monitor measures the dielectric strength of the oil, and as it oxidizes the oil becomes more conductive. Oxidation is usually the limiting factor on oil life rather than additive depletion.


Duke

Interesting, 12k miles and all seems fine.

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I don't know what materials are presently used in engine journal bearings today, but for decades they have traditionally been made of lead-infiltrated sintered copper on a steel backing and plated with a layer of tin. If your bearings look dull-gray when new, this is probably what you have.

So uberwgn's concern about the presence of copper with no lead or tin is valid.

I've seen some modern journal bearings made of sintered copper infiltrated with teflon (carbon tetrafluoride). Too bad fluorine levels aren't in the report.

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95 E320 Cabriolet, 169K

Thanks, guys.



Indeed, and I was relieved to see this when I cracked open the report. The issue has been stuck in my head.

This car continues to run well and provide excellent service and very decent fuel economy. I think we've had the car almost exactly one year and she's done just about 25k miles.

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