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#1
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Logic of MB 2% Soot Limit
First, YES, I've read all the different oil threads (and am beginning to be concerned that I seem to enjoy reading oil threads! )
So, I've read, ad infinitum, that, while certain oils (e.g. Delvac 1) can suspend 4% soot, MB cautions against exceeding 2% soot. So a lot of folks reason that we should abide by what MB says, regardless of what a given oil can handle. My question: what's the logic of the MB recommendation? I mean, if the soot's in suspension, what could possibly be the problem? I'm fine with going with what MB says....I'd just like to understand the rationale.
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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles 06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU 91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete 19 Honda CR-V EX 61k mi Fourteen other MB's owned and sold 1961 Very Tolerant Wife |
#2
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I don't know what MB's logic was, but my concern is that I want to minimize the amount of abrasive particles in my oil. Running clean oil has to be better than running oil with 4% soot in suspension. I cannot prove that higher than recommended concentrations of soot will cause damage, but I would prefer not to find out.
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#3
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I think that's part of my question: if the soot is truly IN SUSPENSION, are there, can there be, any ill effects?
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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles 06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU 91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete 19 Honda CR-V EX 61k mi Fourteen other MB's owned and sold 1961 Very Tolerant Wife |
#4
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It appears to me that soot "in suspension" will circulate through out the engine, including bearings, cylinder walls, etc. The "in suspension" soot is not "dissolved" within the oil, we are still talking about solid particles (although very small) in the oil. IMHO, minimizing the amount of "grit" in the oil has to be a good thing.
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#5
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Quote:
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RIP: 80 300SD RIP: 79 450SEL 2002 E430 4matic (212,000km) 2002 ML500 'sport' ____________________________ FACEBOOK: PANZER450 |
#6
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We all figure that soot is abrasive, but, there's no proof that the size of the particles can have an ill effect if they don't clump together. One of these days I might run the Rotella syn to 8K or so and see how high the iron levels will rise. Is it proportional to mileage, or disproportional? That would be the only way to determine if additional soot levels cause increased wear. |
#7
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What makes you think that?
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#8
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That is the question, and I don't think any of us really know. Personally, I believe less soot is better than more soot, so about 5000 miles is my "comfort zone." IMHO, oil is cheap enough that I don't have to optimize the process.
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#9
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Actually, I consider 2% to be a high soot level. In the course of a reasonable OCI, only an engine in less than good condition would exceed this level. My $0.02, |
#10
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Might go to 6K and get another analysis. It's having silicon issues and I can't immediately determine the cause. |
#11
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#12
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oil replacement
Brian, I would think with the 2.5 qts of oil used and replenished your additive package is kept at a suitable level. I personally have gone to 8k mi in my Powerstroke with it using one quart at about 3500mi and I change the filter at 4k and end up replacing 2 qts+ at that time. Blackstone says I could go to 10k if I wanted to. Having said that, I think the soot levels are a bit less in that engine. However, you might try that and see where it goes with the analysis. JAI(just an idea)
Bud
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1987 300D Turbo, 175k mi., 1998 BMW 323i Convertible, 1997 F250 4x4 7.3L PSD |
#13
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All else staying the same, as soot/solids go up, so does the viscosity of the oil. Given that the oil is already too thick for optimal folow/lubrication at any temperature below 180F, I would consider further thickening a negative. Tim
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2009 VW TDI Jetta Sportwagon 172k miles (rear-ended harder than Elton John on 8/4/13. Total loss) 1991 Volvo 240 142k miles (T-boned by a stop sign runner. Total loss) |
#14
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Part of me wonders...and this is sheer speculation...if, when MB originally made that 2% recommedation, the limit of a decent oil was around 2%. No point specifying a limit that no oil could handle, right?
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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles 06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU 91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete 19 Honda CR-V EX 61k mi Fourteen other MB's owned and sold 1961 Very Tolerant Wife |
#15
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It appears to me that the soot limit is independent of the oil quality. When I had M1 analyzed after 10K miles, the TBN was still about 6, but the soot was getting high. I do not believe that oil brakdown is the limiting factor in these engines.
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