Here are the results of my first-ever UOA, and I need some help interpreting the results! I sent another sample to Blackstone and am having Terry Dyson offer his advice, but this sample was done by Staveley Fluids Analysis. (This is NAPA oil analysis lab.)

9633 miles on oil

19670 miles on truck

I'm using a Mobil 1 M-303 filter and changed it half way through interval. Total makeup oil was 2.75 quarts including 1 quart at filter change.


Iron: 62
Chrome: 1
Lead: 6
Copper: 33
Tin: 0
Aluminum: 4
Nickel: 0
Silver: 0
Silicon: 15
Boron: 46
Magnesium: 440
Sodium: 3
Calcium: 2304
Phosphorus: 1428
Zinc: 1680
Moly: 4
Potassium: 0


Fuel: <1
Vis @ 100: 14.42
Water: 0
Soot: 0.1
Glycol: NEG


TBN: 7.6

Keep in mind that I don't have my EGR blocked off yet--soot looks good!

I'm new to the board, and new to Duramax's. I do work for an oil company and work with oil analysis everyday. Take this for what it's worth...


Iron and copper are really high. If anyone with more DMax experience thinks these numbers are normal please correct me. Silicon @ 15 is higher than I'm comfortable with for my personal vehicle, but shouldn't be enough to explain the elevated wear metals. My first thought was TBN would be low, but I looked again and saw 7.6TBN.

How did you take your sample? Sometimes poor sample technique can show high wear metals. Were it me, I would buy a sample gun and run a mid-drain sample on your new oil in 2,000-3000 miles. Run on a warm engine immediately after shutdown, cut your tubing the length of your dipstick.

I drained the oil at the sampling, so I had a completely warmed engine and caught the sample when about half the oil had drained out, just as the lab instructions suggested.

I wouldn't say that iron and copper are REALLY high for an engine with so few miles on it--the guys over at bobistheoilguy.com are telling me that this is normal for this engine with this many miles. I guess I'll see based on further analysis.

I agree with you that another sample in a few thousand miles on this new oil would be a good idea.

Silicon is a little higher than I'd like, but I'm going to wait for a trend of high silicon numbers before I start worrying.

As soon as I saw you posted this, I thought "I'll bet coyotekid posted this at BITOG too".):h

What kind of oil is this, or did I miss it somewhere? I'll be curious to see what they say at BITOG. Some of those guys are so addicted to oil, I think they sleep with a quart of German Castrol under their pillow. (And I'm afraid I'm heading down that road myself!;))

Never mind. I see it's Delvac 1.

What is the charge for doing these tests?

Blackstone charges $30 for analysis with TBN. AVLube (http://store.avlube.com/oilandfuanki.html) (a supporting vendor here) charges $18.50 + shipping for analysis with TBN.

The NAPA analysis kit seems to be a good deal--$13.50 including TBN.

I've used AV Lube in the past and plan to do more business with AV Lube in the future as well--seems like a great company.

Blackstone is more expensive but also offers really fast service.

I really have no complaints about any of them.

Many engine manufactures set oil condemnation limits for thier engines. Does anyone know if these specs are available for the Duramax?

Before we can call a wear element high or low, the # of miles on the sample must be taken into consideration. For example an engine with iron level of 25ppm (parts per million) and 6000 miles on the sample is actually wearing at a faster rate than an engine with an iron level of 40 at 12000 miles on the sampled oil. The first engine is adding .00416ppm/mile and the second engine is adding .00333ppm/mile.

I'll just have to see what further analysis tells me, but for as new as this engine is and as many miles as were put on that oil, I think this Dmax is actually wearing fine based on my limited oil analysis knowledge. Only time will tell the whole story!

I agree with wear/miles Rich. I like to look at it as wear/1000 miles so that you usually deal with whole numbers. The one other dmax sample that I've seen was taken with 7500 on the oil 30k-40k on the truck. His iron was 8, CU and Al 1or 2. I was hoping those were more typical numbers for a DMAX. No offense intended Coyote, I'm just here trying to learn more about my new truck.

Copper level is high due to the low mileage on the vehicle and the cooling system components (i.e., oil cooler and copper components) are still undergoing a passivation process. This should be watched over time to ensure the copper levels are reducing. If copper levels do not stabilize and then decrease you could be getting continued erosion of copper components. There was a large article about 6-months ago in the magazine "Practicing Oil Analysis" (free subscription) talking about this and the free subscription is worth the effort.

Double L, Practicing oil analysis looks like a great publication. I just signed up. Thanks for the suggestion.

Yes, when only copper is high in newer equipment we tend to write it off as "leaching" from the oil cooler. When other elements are also high it's time to dig a little deeper. The open question is what's high for a low mileage dmax?