Oil Analysis - PeachParts Mercedes-Benz Forum

Brian Carlton · #1 01-30-2004, 11:36 PM

Since I have switched to Rotella synthetic, I was curious to see how it was doing after going 8K miles. I purchased the analysis kit from the local Cat dealer. The results are interesting:

Cat does not provide absolute numbers in terms of percent or ppm. You only get their relative numbers which requires the opinion of the analyst to ascertain whether the level is high relative to other engines of a similar type.

So, all metals including copper, iron, chrome, lead, aluminum, silicon, and molybdenum are all very low. Iron is the highest but still quite low. The additives of calcium and zinc are still quite high.
The most interesting number is the soot. Cat has numbers from 0 to 200. Their comment is that a number of 140 is as high as you would normally want to see. Mine was 160. The overall evaluation was "abnormal" due to the elevated soot levels.

This vehicle always travels above 50 mph except when it is leaving its garage. So, the potential for excessive soot due to lugging at low speeds is non-existant.

So, my conclusion is that a good oil can retain its wear additives for many miles, but, soot is going to accumulate and there is little you can do about it. I am going back to 5K intervals. Everyone who runs synthetics over 10K should take note.

leathermang · #2 01-31-2004, 08:32 AM

"above 50 mph except when it is leaving its garage"......

That is comforting for your neighbors , I'm sure.....

Does that mean you ENTER the garage at above 50 mph ? Is your garage like 140 feet long ..... or do you have a ' Tailhook' arrangement like aircraft carriers..... an ' axlehook' in your case ?

Brian Carlton · #3 01-31-2004, 08:55 AM

Yes Greg, I enter the garage at about 50 mph and the new calipers are so good that they stop the 126 in the 28 feet that I have available.

snoopy007 · #4 01-31-2004, 09:11 AM

I'm switching to AMSoil next week, I ordered two kit for testing I was going to change the oil at 6k. However, I may pull it 5k now. I drive 85 miles a day to work, with ~50 mile of interstate 70-90 mph driving. When I pull the oil I will post my results.

Wasuchi · #5 01-31-2004, 11:13 AM

The soot levels are where a bypass filter of some sort would help (other than the built-in one). I don't know where you would put one under the hood though, there really isn't a whole lot of room even on a 126 I don't believe.

Brian Carlton · #6 01-31-2004, 11:28 AM

Yes, that is absolutely true. If a filter could be added that could remove the soot, the oil has sufficient additives to go a much longer distance. In the previous post, I failed to mention that the oxidation level of 25 was relatively low, as well.

prb51 · #7 01-31-2004, 12:05 PM

Will the low sulpher diesel that is mandated to come on line, not sure of the date, assist in lowering the internal soot levels?

#8 01-31-2004, 10:07 PM

I thought our oil filters were a two stage design, the top portion a bypass and the bottom full flow. I don't think two bypasses will help you, most soot comes in VERY small particles that will pass through the filters. Only the centrifugal type filters are effective in removing some soot.

Use of B20 has shown to reduce soot levels in the used lube oil. Also, the use of Schaeffer's Soyshield fuel additive has reduced soot levels in a TDI. Other than that you can't beat Larry's change hot and change often.

In about 6 months I will take a sample from my 84 300D and share the results. Soyshield in every tank.

JHZR2 · #9 01-31-2004, 10:32 PM

140 is probably similar to a 1.4% soot loading. Typical HDEOs havea soot holding threshhold of around 2%. I know from experience that these engines typically put in 0.8-0.9% soot per 3000 miles. Therefore, in reality you were doing pretty good, but 8000 miles on a 617's oil is probably a bit much. Id take it down to 6000 miles, sample from a different company that gives actual percentages, etc. and see how it goes...

If Fe gets above 40, or Si is above about 15 or 20, the oil is ready to go anyway. Also, you need to know the viscosity at 40 and 100C to see that it hasnt sheared down a grade. Remember, turbos shear the oil down faster than regular cars.
Also, you need to know the TBN, to be sure that the additive package really is still up to par.

JMH

Brian Carlton · #10 01-31-2004, 11:17 PM

Quote:

Originally posted by JHZR2

If Fe gets above 40, or Si is above about 15 or 20, the oil is ready to go anyway. Also, you need to know the viscosity at 40 and 100C to see that it hasnt sheared down a grade. Remember, turbos shear the oil down faster than regular cars.
Also, you need to know the TBN, to be sure that the additive package really is still up to par.

JMH

The actual Fe from Cat was 62 and the Si was 8. The viscosity at an undefined temperature (presumably 70F) was 14.0.

Cat does not measure the TBN, although it does indicate TBN on the printout. There is no number there.

So, clearly, 8K is too many miles between oil changes. I'm going to go back to 5K and see what it does. Anybody know who does oil analysis properly with percentage indicators so we are not guessing?

BoostnBenz · #11 02-01-2004, 12:11 AM

Quote:

Originally posted by Brian Carlton
So, all metals including copper, iron, chrome, lead, aluminum, silicon, and molybdenum are all very low.

Well I believe the molybdenum is there for wear so I'd hope that they aren't to low.

Shouldn't the oil analysis be done in ppm rather than percentage? It seems like that is the way the pros do it when listing oil information.

By using bio or waste veggie doesn't it put some of the fat or whatever in the oil? I recall hearing this as a problem for people who changeover to WVO. Up until about a week ago I never heard of these centrifugal filters, about how much do they cost? Does it matter which way they are mounted? Does there have to be a high volume going through it to keep it spinning?

TomJ · #12 02-01-2004, 12:51 AM

With Bio, the esters have been broken and replaced, unlike WVO/SVO, so no problems in that respect. The schaeffers "additive" is just pure B100, no more and no less. Yes, BD will reduce soot levels, EVERYONE should be running at least B20 (higher in warm climes) in these vehicles, too many benefits not to, directly for vehicle, for enviro, for local economy, etc.

Also, the oil in question is Rotella Synth, purportedly not a "true" synth and my experiences with it have been that it's not even CLOSE to M1 or Amsoil, acts more like dino than a synth (use it in my gasser Jeep since after break in with petro.)

Would like to see this EXACT same engine and test with a true Synth oil and see what comes, if results are same for mileage, then that says something for RT Synth, if not, then that ALSO says something!

tjohn · #13 02-01-2004, 09:19 AM

One thing to remember is that if this was your initial oil change on the synthetic, some of what you're seeing is stuff left behind by the dino that is now being cleaned out. Your next analysis should be a bit cleaner. I know people who report being able to get 10K w/ the OM617 between changes, and 1 guy who gets 15K. I personally, like you, come in around 7.5-8 K with Mobil 1. The limitation is the soot every time.

JHZR2 · #14 02-01-2004, 09:32 AM

Yes, moly is a barrier protection antiwear additive.

Oil analysis should be given in ppm ultimately, but soot loading, oxidation, nitration, for example, are all done on some sort of index or just in actual percentages.

Fe of 62 is a bit too high for my taste, although if you consider this engine is a huge block of iron, it is kind of to be expected at these intervals. Si number is great for 8k, you have a really tight intake that doent let much of any particulates through.

JMH

JHZR2 · #15 02-01-2004, 09:52 AM

The thing is, rotella group III 'synthetic' does not have the esters that cause a majority of the cleaning action. A nice shot of calcium will do some, but the esters (especially polyol esters like found in redline oils) are more aggressive. I have no doubt that the rotella group III oils will have a cleaning action superior to the group I or II/II+ basestocks, because the high severity cracking processes will yield a lube that will not volatize and break down as easily. As such, it ought to not contribute to the junk in the deposits, and hopefully at a hot drain ought to let some come out.

All the same, typically it is true that an oil analysis done the first time with a new oil will show remnants of slop that was cleaned and clashed additive packages which cause some funny readings.

JMH