6.7 cummins major fuel dullution in oil sample

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I just got my used oil report back from polaris labs and it indicated 10% fuel. Yet no excessive wear metals? Viscosity was at 10.9cst at 100C. Right around a 30 weight. This engine has always sheared down to a 30 weight. Ive had used oil samples from blackstone labs done three previous times and had about the same wear metals. they have been slowly decreasing as break in occurs. This last one is higher because I ran 1000 miles more though. I had 20,000 miles on my truck at the time of my report. I guess I should send in my latest sample I took a couple weeks ago when I changed the oil. They didn't even get the sample date correct. I think the 10% is a typo. Either that or blackstone is wrong about their fuel dillution testing methods. This is the 4th uoa on this engine and it has always sheard the oil down to a 30weight. I kind of want a refund on this uoa. I think they forgot a decimal. I would think that the wear metals would reflect the high fuel dilution but according to my previous oil samples the engine wear is pretty normal. Iron is a little higher though but not much. Here are the wear metals and all the other things they flagged. I couldn't put the entire uoa on here so I just put mostly the wear metals and a few other things I thought were weird.

20,665 miles on unit
Miles on oil: 4400
Hours on oil: 200
Iron: 40
Chromium: 1
Copper: 3
Lead: 0? No bearing wear????
Silicon: 4
Sodium: 3
Potassium: 0?
Fuel: >10%
Soot: 0.9% Oxidation: 16 Moderately critical
Nitration: 27 Critical
 
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I thought anything above 6% causes excessive bearing wear? But yet I don't see any excessive bearing wear. I called them up and they are going to retest it cause I thought some of the things on the report looked weird.
 
Originally Posted By: bullwinkle
I would have them retest it-does it seem like it misfires at all? 10%+ is even high for a DPF equipped truck-sounds like potential injector problems.

No it runs fine. Ive put another 4000 miles on the truck since the last sample. I guess I should send my latest one in. This sample was taken back in April. I just sent the sample taken in April in a few days ago.
 
Iron is kinda high for 4,400 miles is there lots of idle time? 200 hrs for 4,400 miles.

Soot: 0.9% Oxidation: 16 Moderately critical
Nitration: 27 Critical
 
If this is a DPF equipped truck, I'm betting on the regen cycles causing this.

2011 Duramaxes have added an extra (9th) injector in the turbo down-pipe after the turbo to keep the extra diesel fuel needed to regen the DPF out of the sump and presumably spare the turbo of that superheated exhaust gas. I take this as proof that the first generation DPF equipped diesel design was a poor, band-aid attempt at emissions compliance.

Unfortunately for first generation DPF equipped trucks, they just programmed extra injector pulses into the fuel map during regen to superheat the exhaust, thereby inadvertantly flooding the sump with extra diesel fuel as a byproduct of the regens.

First generation DPF'ers (like me) got a bad deal here. Just waiting for my warranty to expire so I can remove this system.
 
I guess blackstone isn't very accurate in testing for fuel contamination. Since the first three tests showed everything was basically fine. Unless something went wrong on my truck in the last 4,000 miles since the previous test.
 
Originally Posted By: Steve S
Iron is kinda high for 4,400 miles is there lots of idle time? 200 hrs for 4,400 miles.

Soot: 0.9% Oxidation: 16 Moderately critical
Nitration: 27 Critical

They didn't flag oxidation. I didn't mean to flag that one. This truck is mostly driven in the city. I do go to school about 10 miles away. takes about 25-30 minutes to get there. 8 of the 10 miles I spend going 60mph. The truck then sits for about 3 hours and then I drive home. So it doesn't cool down all the way. I always try to make sure the truck gets up to temp to burn off any moisture/fuel.
 
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Originally Posted By: motor_oil_madman
I guess blackstone isn't very accurate in testing for fuel contamination. Since the first three tests showed everything was basically fine. Unless something went wrong on my truck in the last 4,000 miles since the previous test.

Probably cannot assume it was a blackstone error. It's hard (or impossible?) for me to believe any lab would miss a 10% fuel dilution. That's kinda crazy. You sample bottle wasn't by chance contaminated, was it? If not, time for a retest.
 
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I don't see how I could have contaminated it. Unless polaris did somehow.
This last uoa was tested by polaris labs. I have three previous ones done since the truck had 8700 miles on it done by blackstone. Maybe i'll post them up. All those had sheared to a 30 weight too.
 
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These trucks do inject fuel on the exhaust stroke during regeneration mode. From what ive heard it does cause fuel dillution and cylinder washdown. But I haven't noticed any excessive fuel dillution until this latest sample.
 
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Polaris thinks it good be a bad injector. Wouldn't I notice the truck running rough/bad if I had over 10 percent fuel in the oil?
 
Steve S the truck doesn't hardly every idle anymore than 5 minutes at a time. It's not like what most people do with their diesels where they let them idle for hours on end.
 
Looks like your average speed is 22 MPH, meaning you are putting city miles on your truck. When my Duramax is in regen and I'm stuck in traffic, I'll drop anywhere from 8-22% oil life during the regen especially when it's really cold out. If I happen to be on the highway, I can get a regen done in 2% oil life.

I have been advised by a GM rep that this differential takes into account the amount of fuel dilution resulting from regens while the engine is under only slight load (in the city).

I watch my odometer and fuel economy computer (and smell for diesel fuel) and I can tell within 1 to 4 kilometers of when a regen begins. Unfortunately, when this happens, I try to get it out on the freeway for about 20 miles at 65 MPH or better to get that regen done quickly.

This is what my GM dealer advised me to do. It's a ridiculous pain, but it's enabled me double or triple the number of miles that my OLM permits me in my OCI.

FWIW, you may consider this strategy if your 6.7 regens with Diesel fuel and not the bluetek urea.
 
I just don't understand what caused it to stay in the .50 to 2.0 percent fuel dillution range ever since I have been sampling and then decide to jump up to 10 percent. I have polaris retesting it so I guess we will see how it turns out. Hopefully it's just a typo. If not then i guess I will know why the oil has always sheared down to a 30 weight.
 
injector failure could have happened at any time, or any other issue that could have caused the high fuel dilution. if uoa numbers are correct then it would be my guess that whatever is causing the fuel dilution would have had to have happened fairly recent.

since other numbers on the posted uoa are within spec, and i'm assuming the truck is still within its warrenty period, i would take the truck, along with uoa to the dealer for a diagnosis
 
Maybe I should just sell this POS. It's one thing after another with this truck. I really like diesels but I guess I just bought the wrong one. Already had the turbo cleaned then replaced 50 miles later. Computer reflashed about 10 times. DPF full, 02 sensors replaced. Whoever heard of 02 sensors on a diesel? Egr system cleaned out twice and egr cooler replaced. I'll just have to live with a gas engine since you can't find a low mileage 5.9 cummins anywhere for a good price. They all have 100,000 miles and still want 30,000 grand!
 
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