2003 Duramax, M1 T&SUV, 6033mi/59905mi

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Owego, NY
2003 Chevy 2500HD, 4X4, Crew Cab, Short Box, Duramax 6.6L Diesel, Allison Transmission, OilGuard Bypass Filter

Mobil-1 Truck & SUV 5w40; 59,905 miles on Engine; 6033 miles on oil.

Sample Date: 8/13/2006
Test Date: 8/17/2006
LAB: PREDICTIVE MAINTENANCE SERVICES, INC. (AVLube)

Iron: 7
Chromium: 0
Lead: 6
Copper: 7
Tin : 0
Aluminum: 2
Nickel: 0
Silver: 0
Silicon: 6
Boron: 69
Sodium: 2
Potassium: 4
Magnesium : 592
Calcium: 2,134
Phosphorus: 1,428
Zinc: 1,686
Moly: 0
Fuel: A (0-3)
Water: Glycol: Neg
Visc-100c cST: 13.4
TBN: 10.7
Soot: Oxidation: 12.00
Nitration: 6.00

UOA HISTORY

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Bill, any comments on ratio of lead to iron? My last Dmax analysis had lead at 4 and iron at 4. A comment was made that there might be a "problem", due to the ratio of iron to lead. They said as a rule, lead should be half of iron. At 4 ppm, I don't think it's anything to worry about with a 7200 mile OCI.
 
Iron will go up with the amount of time the oil spends in the engine along with any ferrous wear metals. Typically the only iron wear will come from push tubes, cam followers and rocker arms and these are not typically high wear items on modern diesels. Most valve train wear will occur because of high soot or low viscosity oil, which doesn’t seem to be a factor in your engine.

Silicon is low so the air filter and intake plumbing are solid.

Lead and copper are both a good number for 6000 oci. I wouldn’t worry about them at all. Everything looks like it is wearing nicely. Did you change the oil or just take a sample? With good TBN I’d keep going and re-sample in a while.
 
Thanks for the feedback ..
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Oil was changed at this sample ... I know it could stay in longer but I'm currently doing about 12-15kmiles per year so I like to change the oil every 6 months or so. TBN also got a boost when I topped off with a 1/2 qt of PS Diesel Lube Oil Extender.

Pick,
I haven't heard about the Iron/Lead ratio criteria .. sounds interesting ... Clicking on my UOA History link above shows how the ratio has been running since new ... both Pb and Fe have been fairly low but don't meet the 2:1 ratio.. maybe the 2:1 Fe/Pb rule applies more to engines with higher wear rates ???

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Bill,

The amount of Fe wear is so low here, I think you can discount the 2:1 ratio theory.

I'm also curious why you're only running 5k-7k OCI's after reviewing the oil analysis history of this engine??? You could easily do the 12k-15k with the bypass filter and synlube combo, based on the changeout numbers I see here.

It's interesting that the trace (5-15 ppm) of potassium only started showing up when you switched labs from OAI to AVLube. This makes me suspect the K is merely an artifact of the testing process and not a contaminant of any kind.

Had you stuck with the Amsoil, HD Diesel and Marine oil, I think you'd see similar numbers. However I can understand the desire to use an SAE 5w-40 for winters in upstate NY. My Dad lives about ten miles north of Cooperstown and I know how cold it gets up there (can't say I miss it!)

Nice database by the way - I knew without looking you had to be a engineer....

TS
 
TS,

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... good engineer observation ... we can't hide ...

Regarding the OCI, I know I could go longer but I guess I have a "Compulsive Oil Change Disorder" .. I came of age in the 60's with 2kmi oil changes .. stretching to the 6-7kmi OCI was hard but I'm slowly coming around ..
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