Acceptable levels of wear metals and contaminants

[paulri]

Looking over all the UOAs that people post here, I often wonder what constitutes acceptable or normal levels of iron, or insolubles, or water, or how low the TBN can get before the engine is damaged.

Has anyone done any studies that correlate numbers of wear metals, to actual engine wear, or damage? I see Blackstone in their UOAs will put high numbers in boldprint, but I wonder what exactly that is supposed to tell us. I will call them and see what they have to say about it (if they are willing to communicate this). I realize that in Blackstone’s reports, they do have a column of what the average is, or what they like to see as a maximum or minimum. But my question would still be, what is the basis for saying that 9 ppm of iron is ok, but 40 is too high? Do chances of engine wear, or part failure, increase by 50% when iron gets that high? Has anyone identified UOAs of cars that had engine failure, and noted certain levels of iron, silicon, etc.?

 

[paulri]

Just found this: http://www.bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/

I'll read it tomorrow and see what is has to say about my OP.

 

[Garak]

Also, read this and just about anything else you can get your hands on that Doug wrote.

 

[paulri]

Just finished the piece I linked to.

One major point I took from it: if iron (in ppm, per 1000 mi) is actually declining over time, that must mean that there is no additional wear from these particles, or others such as insolubles or silicon. In fact, that article, breaking down UOAs for a few different engines (hundreds of UOAs were cited) indicated that the rate of iron wear per 000 miles actually decreased up through 10K miles in the only 3 engines that had a breakdown showing wear in terms of ppm per 1000 miles. When the rate is either declining or stable, that must mean that there is only normal engine wear, and that it is not being affected by the presence of these wear metals (that are increasing in the oil, in absolute terms). That sounds acceptable to me.

OK off to the article you linked to.

 

[paulri]

Unfortunately, a search for "Doug Hillary" on this site, gave me only the article you linked to.

I have bookmarked a search for his posts. He's got some 5000 posts, so that looks like a bit of reading.

 

[m6pwr]

http://digital.ipcprintservices.com/publication/?i=106542 good article on acceptable limits, aka condemnation limits.

 

[paulri]

Originally Posted By: m6pwr
http://digital.ipcprintservices.com/publication/?i=106542 good article on acceptable limits, aka condemnation limits.


That was an enjoyable read. If I understand it correctly, they mentioned a lot of different factors that might lead someone to change the oil, but didn't give particular numbers about wear metals (or anything else).

 

[Garak]

Originally Posted By: paulri
He's got some 5000 posts, so that looks like a bit of reading.

That is true. Pay attention to what he says in the UOA threads, most of all, and you can learn a lot there.

As for particular numbers with respect to metals giving a condemnation level, that is problematic. There are so many different platforms and so many different oils and so many different operating conditions that it is exceedingly difficult. Doug set a certain level for iron for his trucks, but that wasn't just some number he arbitrarily grabbed out of the air or from unrelated UOAs.

 

[Shannow]

http://www.e-digitaleditions.com/i/572212-machinery-lubrication-sept-oct-2015/30

 

[paulri]

Originally Posted By: Shannow
http://www.e-digitaleditions.com/i/572212-machinery-lubrication-sept-oct-2015/30

Interesting. This article gave as an "upper warning level" for iron (in truck engines, going 47K) 80-180 ppm. I was surprised that this level was that high, when Blackstone will often flag iron that is in the 40s (or course depending on the OCI).

I guess the idea is that so much iron would not imply excessive wear has already taken place, nor would it cause any additional wear, but that it would be the linear wear that iron shows in oil, lasting for that many miles. Correct?

 

[paulri]

Originally Posted By: Garak
Also, read this and just about anything else you can get your hands on that Doug wrote.


This one is a doozy: http://www.bobistheoilguy.com/forums/ubb...sed#Post2611881

Puts a lot of stuff (including my question) into perspective.

In fact, a lot of that thread deals with what I'm trying to look at here.

 

[paulri]

Another thread dealing with this question. Sure enough, Doug showed up in that one too:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2065149#Post2065149

Gotta say that my heart has been skipping a beat every time I look at a blackstone report with a boldprint number or two. Now I'm getting some perspective on this.

Thanks for the suggestion to look for Doug's posts.

 

[Garak]

Yes, Blackstone's bold printing sometimes is a bit of a false alarm. Sure, there are things to watch for with respect to numbers in a UOA. If one isn't and never has been using an oil with a sodium based additive package, I'd be concerned if sodium and potassium started showing up. I'm not necessarily going to tear into the engine five minutes later, but it is something to think about.

A little bit of iron or copper here and there has to be taken in stride, particularly if you don't have trending going on. That's where the trending does help. Excess lead could be a particle streak, a strange additive, leaded racing fuel, or something that's legitimately a problem.

In Blackstone's defence, while they may know what they've done for UOAs for an individual, they will likely have limited knowledge of the history of the vehicle's maintenance. Ideally, one should have a VOA of the lube being used, and then carry on with that lube all throughout.

They get piles of samples from guys using one brand one time and switching viscosities and brands the next time, only to switch again the third time. So, it's not easy for them to offer advice. They have to offer "safe" advice.

Yes, Doug's posts are exceedingly insightful, and we're lucky to have him.

 

[Clevy]

Before you can say anything is high or low you must develop trends. Then as trends develop you can compare each used oil analysis against these established trends.
Contamination such as insols is best the lower it is as well as most every other value.
As far as wear metals go you can't just pick a number and say it's high or low. Each engine and operating condition is different therefore your particular conditions must be established and compared.