Bentley GTC OEM at 3,000mi

Status
Not open for further replies.
AEHaas

AEHaas

Joined
Jan 9, 2005
Messages
1,623
Location
Sarasota, Florida
This is a new Bentley GTC UOA at 1, 2 and 3,000 miles taken from the OEM oil. The first factory scheduled oil change is at 10,000 miles. My plan is to run a UOA every 1,000 miles for as long as I can stand not changing the oil or to 6,000 miles, whichever occurs first. No oil was added.

The engine is a 6.0 liter twin turbo W-12 with 550 BHP, compression ratio 9:1, top speed - 198 MPH and 0 - 60 dash = 4.8 seconds. The curb wt. is 5,500 lbs., EPA 11, 24 MPG,

......................1,000 mi.....2,000.....3,000.....4,000.....5,000.....6,000
......................................................................................................
Iron__________22________23____33
Chromium _____ Nickel _________1________2_____2
Aluminum _____5 ________7_____6
lead __________ 1________1_____3
Copper ________32_______34____41
Tin ____________5_______3______3
Silver ________ Titanium _______ Silicon ________ 37_______34____39
Boron _________228______195____219
Sodium _______ 15_______12_____13
Potassium _____ Molybdenum ____91______81______92
Phosphorus ___1027______936____1035
Zinc ________ 1151______1027___1182
Calcium _____ 3228______2915___3301
Barium _______ Magnesium ____22________21_____29
Antimony _____ Vanadium _____ Fuel %Vol _____1.5______ Wtr %vol ______ Vis CS 100C __ 12.3______12.1____12.1
SAE Grade ____30________30_____30
Gly test ______Neg_______Neg____Neg
TBN ________not done____NA_____NA
Obs Oxid______23_______27______29
Abs Nitr_______10______13_______14
Fuel soot______NA______NA______0.0

Test lab was: youroil.net

aehaas
 
Looks fine to me. It's probably M1 0w40. It would be nice to see a PQ for the particle size. As I've recently learned, some of what we see in these reports is actually chemical wear that is mostly particles that are extremely small in size. More of a chemical wear.
 
AE,

Definitely M1 0W40 with all that Boron. Ca,Mg and Zn look right

Your nitration climbed quickly, indicating that the rings are not yet sealed. I'd want to change the oil out and then drive the engine hard to seat the rings.

Silicon is also high. I'd want to get that out of there.
 
Interesting comment about nitration. Si in a new engine can be from silicone sealants rather than abrasives. I agree with Buster that it is hard to tell from UOA whether what you're seeing in the wear metals numbers actually represents wear.

What mileage does this car get in use so far?
 
Originally Posted By: buster
Looks fine to me. It's probably M1 0w40. It would be nice to see a PQ for the particle size. As I've recently learned, some of what we see in these reports is actually chemical wear that is mostly particles that are extremely small in size. More of a chemical wear.


Buster, it's all wear, whether chemical or physical, and is measured in ppm by weight. In either case, metal is removed from bearing or sliding surfaces. However, you have no way of discerning whether this analysis is showing "chemical wear" or frictional wear, or a combination of both, without using multiple analysis methods. One method that I have written about, is to use ICP spectroscopy and Rotrode spectroscopy to help inexpensively discern the predominant wear particle sizes. Blackstone labs uses ICP spectroscopy. Dyson's lab uses Rotrode spectroscopy.

Having said that, this looks like normal break-in wear to me. And based on the data presented, the rings are not yet sealed completely, and there is a considerable amount of fuel dilution. This seems to be common for newer VW/Audi engines, which is the base engine that the Bentley is built on.
 
Originally Posted By: glennc
I agree with Buster that it is hard to tell from UOA whether what you're seeing in the wear metals numbers actually represents wear.


Glenn,

Of course it's wear. And if AE posts more UOAs on this engine, we'll see the normal asymptotic decline of the break-in wear curve, assuming that he changes oil and does analysis at uniform regular intervals.
 
Last edited:
The government giving us conflicting information? I am not buying it.
56.gif


Dr. Haas, I am curious as to what the "gas guzzler" tax runs someone on a car like this.
 
Last edited:
Why does the Moly, Phosphorus, Zinc, and Calcium go down and then back up from 1,000-3,000 miles?
 
It would be nice if labs gave us the variance of the tests. A value such as Fe = 10 should be given as Fe = 10 +1 -2, or some percentage as Fe = 10 +10 -20 percent.

aehaas
 
What about particle size and the idea that ICP spectroscopy only shows 15-25% of the particles in the oil?

Seems to be different schools of thought on how beneficial oil analysis really is at comparing wear levels among oils.
 
Buster, you are correct that ICP spectroscopy only shows particles in the oil less than .5 to 2 microns in size. Larger particles will not be seen in the analysis, but larger particles that have broken off, due to friction events, will themselves be abraded as they pass through bearing surfaces and increase the level of smaller particles. There is therefore some correlation between ICP measurements and larger particle wear, but it is not 1:1. Just because ICP does not measure all particles does not make it worthless for comparison purposes. However, there is another way.

That's why I like the method which Terry's contract lab uses, which is Rotrode emission spectroscopy. There are 2 advantages to it. First, the oil sample does not need to be diluted. It is measured directly. This is an advantage, since there is no possibility of operator dilution error, or contamination of the diluting oil. (This does not preclude other human error or contamination. But it does reduce the possible sources of error. As a result, I find Terry's Rotrode results highly repeatable.) Second, the particle size detection limit for Rotrode is much larger than ICP. Thus a larger percentage of particles are measured.

Here's a description of the differences between ICP and Rotrode from the MRT Laboratories website.

Quote:
The Rotrode Spectrometer has a particle size detection limitation of between 3µ and 10µ (depending on the particular metal in question and the amount of surface oxidation on the particle surface) compared to the .5µ - 2µ limitation of the ICP. Results of the Rotrode Spectrometer are accurate to about 1 or 2 ppm. Results of the ICP are accurate to .1 ppm. The advantage of the Rotrode Spectrometer is that no dilution of the sample is required, while the advantage of the ICP is its accuracy. With proper sample preparation, an ICP can measure in the 10's of parts per billion (ppb). Particle size limitations of an ICP are even more sever than a Rotrode Spectrometer because the sample and particles have to be nebulized. If measuring very low concentrations, the diluent (usually diesel fuel) has to be at least as clean.



For either method, there is no lower particle size detection limit. But there is a lower ppm threshold. ICP is capable of detecting particle dilutions of down to .01 ppm, whereas Rotrode has a higher limit of about 1 to 2 ppm.

So Rotrode can detect particles as large as 3 to 10 microns, whereas ICP has a size detection limit of .5 to 2 microns.

It is also possible to use the two analysis methods together to determine the percentage of larger particles in the sample. The larger the difference between ICP and Rotrode, the larger the average particle size.

There is yet a 3rd method which provides even better resolution of large particles, and that is Rotrode Filter Spectroscopy, which can detect particles between 5 and 150 microns in size. It appears that only a few private labs have started to use this method, which is designed to be used along with one of the other methods.

Here's an article on particle analysis.

Oil Analysis vs. Microscopic Debris Analysis: When and Why to Choose

If you look at Figure 3, the problem you alude to is shown. Standard ICP spectroscopy has a cut off of about 2 microns. Wear particle distribution from all forms of wear (Benign, Severe, Advanced and Catastrophic) do not evenly distribute across all possible particle sizes. So, when Severe where begins, almost all the particles are concentrated above 1 micron. Thus ICP Emission Spectroscopy will not be able to detect much difference from the baseline Benign level, unless wear advances to the advanced stage, where larger particles have been further broken and abraded to smaller sizes that are detectable.

If this is the case, any major change in ICP particle concentrations is a big deal, since it indicates that something major has changed, whether it be an actual wear problem, or some "issue" with the oil. Even then, the "issue" may be benign, and not constitute a long term reliability problem.

Rotrode spectroscopy increases the detection range up to the 2 to 10 micron range. As you can see from the Plot, this will allow more than just Benign wear elements to show up, and reveal severe wear particles. At the same time, the concentration of benign particles starts to drop off and changes to a predominance of larger severe particles. In this case, Rotrode emissions spectrography will pick up the larger particles. And, as I've said before, if combined with ICP will tell us whether there is a larger particle concentration above 2 micron, indicating greater "real" wear. Terry Dyson chose the Rotrode method specifically for this reason. It does have enough larger particle sensitivity to reveal issues that the ICP method will not ... until problems have advanced.
 
RI, thanks for providing that information. Ideally, one should want low wear metals regardless of size/shape etc.

The issue I have with all this, most engines and oils don't have wear control problems in a well maintained, well built engine - Toyota/Honda etc. Fuel dilution seems to be more of the problem here, in which "some" oils apparently handle this problem better than others.

http://www.swri.org/4org/d08/ILSAC GF4 Summary Sheet.pdf

Sequence testing also relies on a lot of component measurements and other important aspects of what makes a quality oil that oil analysis can not interpret.
 
http://www.swri.edu/4org/d08/GasTests/iiig.pdf

In the CJ-4/Seq IIIG test, critical components are visually inspected, but oil analysis is also used.

At the end of the test, all six pistons are
inspected for deposits and varnish; cam lobes
and lifters are measured for wear; and oil screen
plugging is evaluated.

Kinematic viscosity increases at 40°C are
compared to a new oil baseline (% increase)
every 20 hours. Wear metals (Cu, Pb, Fe) are
also evaluated at this interval.
 
Status
Not open for further replies.

Similar threads

AEHaas
  • Locked
Bentley GTC OEM, GC at 3,000mi & 6,000 mi
Replies
15
Views
8K
AEHaas
Back
Top