Wear Increases After OC?

[kschachn]

True, it does make a direct measurement of the cam lobe. Depending on the API rating/license certification as time went on, the max wear limits have changed. Seems to have went down from around 120 um to 60 um (micrometer) from what I can find. Also the ASTM D6891 is ran for only 100 hours, and it's done on the fired engine at very low RPM (800 & 1500 RPM) where the wear rate would probably be pretty low compared to much higher RPM.

The ASTM D6891 does reference also making an "iron wear metal concentration" measurement ... so UOA. But doubt it's used as part of the criteria to pass or fail as the direct measurement is the primary factor. Wouldn't know how the UOA comes into play without seeing the entire ASTM spec, which I'm not going to pay to see, lol. In a test like this where the engine run time is pretty low time and low RPM in the scheme of things, obviously a direct wear measurement is the best way to do it.

I'm wondering if any controlled tests have been done that do a much more long term engine wear test (like 100K+) on their chassis dyno (like Mobil, BMW, etc do) and they take regimented UOAs along the way as monitoring data/info before the test ends and they do a final tear down, inspection and measurements. Seems like controlled UOAs would be beneficial information in a very long term test like that.

ASTM D6891-21e1

Standard Test Method for Evaluation of Automotive Engine Oils in the Sequence IVA Spark-Ignition Engine

www.techstreet.com

"The primary result is camshaft lobe wear (measured at seven locations around each of the twelve lobes). Secondary results include cam lobe nose wear and measurement of iron wear metal concentration in the used engine oil."

Yeah sorry I no longer have access to all the ASTM tests. But even if they do use spectrographic data here it is a controlled test, unlike UOA from street vehicles. Street engines have a host of sources for wear. But if all you wanted to know was “wear” then maybe you’d get something.

Thanks for the discussion here.

 

[ZeeOSix]

Simply put, no, I am not. I am responding to DNewton's question.

You sure seem to be based on your post I responed to. You sound like you believe a UOA should tell you how much wear has happened on engine components, and tell you when they are worn out.

 

[dnewton3]

David, thanks for your detailed and thoughtful responses in this thread.

And I thank you; your knowledge is not without merit!
As is Zee's as well.

I may differ in my opinions from each of you occasionally, but I am no better than either of you. I appreciate the professional exchange of ideas with fervent intensity, yet it's always a handshake at the end!

 

[CarbonSteel]

You sure seem to be based on your post I responed to. You sound like you believe a UOA should tell you how much wear has happened on engine components, and tell you when they are worn out.

Again, I am answering his question. Nothing more and nothing less.

 

[ZeeOSix]

Yeah sorry I no longer have access to all the ASTM tests. But even if they do use spectrographic data here it is a controlled test, unlike UOA from street vehicles. Street engines have a host of sources for wear. But if all you wanted to know was “wear” then maybe you’d get something.

Thanks for the discussion here.

Yes, wear is wear ... and that's all a UOA will show, within it's measurement limits (narrow window as dnewton3 explained). If an increase in "ppm Fe per 1000 miles" has happened compared to past trend data, one can only conclude that more wear rate has occurred compared to the other UOAs trend. It won't tell you what caused the wear. On-going regimented UOAs to build a trend on an engine would seem to have some value. Just doing a few UOAs over the life of the engine isn't going to tell much about wear trends, only the properties of the oil itself.

 

[TiGeo]

Per @ZeeOSix post above, here are my UOAs since new on my '18 Sportwagen. You can see the wear metals trends correlate nicely with the installation of new(er) turbos and then the broken timing chain tensioner. The bottom line to me on UOAs are that you need lots of data to say anything/develop trends to compare against and it's not cheap to collect it at ~$30 a pop. This car, based on its use and modifications gets them each oil change. All oil has been xw40 Euro VW502 etc. approvals with some brand switching but primiarly Liquimoly products including additives (MoS2/Ceratec). HPL for the last year. I did a bit of experimentation with M1 and QS as well mainly looking at viscosity drop over an interval.

Post here:

Aluminum flecks in oil filter

Cut open my Mann oil filter for my Sportwagen today after changing the oil at about dead-on 5K miles/3 mos. Last UOA showed increased aluminum numbers, it was a mid-OCI UOA after a trip down to GA for a VW event where it was used hard on the roads with "dragon" in the name. Quite shocked to see...

bobistheoilguy.com

 

[dnewton3]

To all -

I want to clarify something, if it's not already illuminated in my many posts in this thread.

I state unequivically that "wear rates" are higher at the very front end of an OCI. This is likely due to two things:
- TCB removal making for a slight uptick in wear
- residual oil which "taints" the reading because the miles are so low that the echo from the previous load is skewing it slightly
How much does each contribute? Dunno. I have no way to discern that in a UOA study. And there's not one SAE study I can find that addresses this as the study topic.

But here's something else I will stand by firmly ...
That slighlty higher wear trend is NOT, by any means of measure, anything to concern yourself with. The higher wear rate is typically only 1ppm higher than what it would be at 10k miles. As an example, using my database of all UOA, of Fe wear:
at 3k miles; 3.4ppm/1k miles
at 5k miles; 2.8ppm/1k miles
at 7.5k miles; 2.6ppm/1k miles
at 10k miles; 2.4ppm/1k miles
at 15k miles; 2.3ppm/1k miles
IN NO WAY should anyone interpret the higher wear rate at the front of the OCI to mean that it's dangerous or destructive.
It is just a statement of fact; the wear rates drop as the OCI matures. The data is indisputible.
What I often find objectionable is that people often say that fresh oil is always better for an engine; that is obviously wrong. Whereas you may be able to say that fresh oil doesn't really hurt an engine, it clearly does not "help" an engine in terms of wear rates. It may be better in terms of fresh additives being able to deal with contamination; that would be up for conversation. But there is ZERO proof that fresh oil is better than used oil in terms of wear rates; the data simply proves it otherwise.

Further, while I do realize some folks object to the Ford/Conoco study, there was also a very interesting bench test they did on the valve-train loads, using the used oil and components. The frictional loss (as measured by a torque sensor on the electronic drive system) when using the higher-mileage oils was an order of magnitude lower! IOW - it took 10x less energy to drive the valvetrain with the mature OCI oil versus "new" oil. Now, I'm reciting that by memory, as I haven't read the study in a while. But that stuck with me ... a 10x improvement in friction reduction with the mature oil TCB in place. That coincides with the claim of reduced wear rates as measured by the electron bombardment and UOAs.

If I were to summarize this topic, it would be thusly:
- Fresh oil changes do induce some manner of escalated wear rate, but we have no ability to attribute any portion of the phenomenon to any one cause (TCB removal or residual as the two contributors). However ...
- It doesn't matter, because even the "higher" rate at the front of the OCI is meaninglessly low enough to not cause concern; it's a moot point. So folks need to get over it and find something else to worry about.

 

[ZeeOSix]

I do think UOAs have their place (I have run nearly 100 in my time), but I cannot take that data and say in x miles I will need to replace anything in the engine unless there is a part that causes the readings to suddenly rise.

Have you ever calculated the wear rate of all those UOAs and plotted the data on the same engine? I'm betting they were not all done on the same engine, but seems you would have quite a few UOAs out of 100 total on the same engine to analyze wear rate trend data.

As said before, UOAs are only useful to look for changes in wear rate trends on the same engine. If the UOA trend starts a noticeable uptick in the wear rate, then more investigation should be done to try and determine why ... just like @TiGeo did with his UOA trend data.

 

[TiGeo]

Per the commentary and not sure why I haven't done this before....here are the Fe and Al values per 1,000 miles. The large increase after the new turbo at ~45K makes sense vs. the used one at ~20K b/c well...it was new so more initial wear would be expected as it broke in (should have used that Liquimoly Turbo additive!!!).

 

[ZeeOSix]

^^^ Yep, plotting "ppm/1000 miles" is a better way to see the wear rate trends.