Engine Wear and UOAs

[1sttruck]

This is a followup to a few other threads on UOAs, films, and wear. One article had an interesting chart on engine output differences due to normal (?) and extended oil changes.

http://www.practicingoilanalysis.com/backup/200211/Editor-Fig3.gif

The article made several points about wear due to particles, and that just using a bypass could result in noticeable fuel savings, longer engine life and lower emissions. Looking at the chart one could assume that a change interval midway between the two would result in engine life midway between the two, for a first approximation. A question is would UOAs detect the differences in the oils at the change intervals, and even if it could, would people recognize the potential for decreased engine life ? Looking at a few bypass UOAs I don't see dramatic differences across the board, in fact there seems to be an attitude that 'dirtier' oil is expected as the change interval is being extended. Using a synthetic won't help the situation much as it's assumed that the wear is due to soot and particles.

 

[427Z06]

You have a link for the article?

 

[jason07-1zzfe]

Over 20% HP loss in visible range? I don't believe it for a second. Maybe if they used some SG ValueCraft oil for that 25k miles (mixed with tar!).

 

[NEPA_Z]

I don't play an engineer on TV, but I am one, and methinks that chart is crapola...

 

[1sttruck]

http://www.practicingoilanalysis.com/article_detail.asp?articleid=401&relatedbookgroup=PowerGen

 

[1sttruck]

http://www.machinerylubrication.com/article_detail.asp?articleid=238&relatedbookgroup=PowerGen is the article referenced in the previous link

 

[1sttruck]

Here's a link for a heavy duty Volvo manual, which has the same general statement about using synthetic oils or oil analysis that Cummins makes for my engine, which is use doesn't allow for extended oil change intervals. Warranty is one thing, practice seems to be another. Gas engines don't have to deal with the diesel soot but particle contamination is still there.


http://www.volvo.com/NR/rdonlyres/F8FBB7F0-698C-4799-9038-0329AE46A665/0/PV776_TSP20154789_lores.pdf

Synthetic Lubrication

Synthetic oils are offered as an alternative to the traditional, petroleum based oils for engines. These oils may be used in Volvo engines, provided they meet the quality levels specified on the previous pages, that is: API CG-4, CH-4, VDS or VDS-2. Product information about synthetic oil should be reviewed carefully. Their use does not permit an automatic extension on recommended oil change intervals. The ability to protect the engine is better in some ways compared with petroleum based oils but its lifetime in the engine is the same. This is because of the combustion by-products that contaminate the oil. These contaminates will make the change intervals the same as for petroleum based oils. The use of synthetic oils does not permit the extension of the recommended oil change intervals. Synthetic oils offer improved low temperature flow properties and high temperature oxidation resistance. They are generally more costly than petroleum based oils. However, in extreme driving conditions, that is, in extreme cold or in desert operation, a synthetic oil may be the only choice for the application (see next page about viscosity).

 

[jsharp]

Particle contamination is stil there in a gasoline engine, but not to the same degree as with large diesels. They are talking about contaminate levels that are large enough to plug oil filters and put them in bypass all the time. I doubt any of us have seen this with what we call "extended drains" in our auto engines. The recommended drains they use as a baseline are far longer than all but a few people here have run in gasoline engines.

I know I've never run any oil in any engine 25K miles, let alone 50K or 60K...

 

[1sttruck]

But considering differences in sump size the 15k miles for the new Mobil PCMOs is pretty agressive, and it appears that people will still need to deal with contaminates even if soot isn't present.

 

[jsharp]

I don't think a 15K interval with the new M1 formulations is all that aggressive. A lot of us have run 10K miles with the older M1 oils and had UOA's that looked just fine. A lot of the Amsoil guys have been running this far for years too.

As has been mentioned before, it's likely there's very little difference in practical engine life between a UOA that shows 6ppm of a given wear metal or contaminate and one that shows 12ppm. Sure, the change is 100% but the overall levels are so low that depending on what the particles are, it just doesn't matter...

 

[Gary Allan]

Help me out here.

Is this comparing two identical engines, one that received 12k OCIs and one 25k OCIs for 300k and 250k respectively ..but the 25k engine had the sump reduced 10% (assumed for the entire 250k)

Isn't that like having two patients and two doctors?? One set you give a sterile surgical suite, fine surgical tools, a scrub nurse, and state of the art monitoring equipment ..and the other you give a flashlight and a rusty razor blade inside a dumpster and then determine success by how the patients survive the experience??

..or did I interpret that incorrectly??

 

[1sttruck]

The Cummins N14 appears to be a 14 liter engine with a 9 gal sump, typically 8 gal for a change. A 10% reduction in sump is 0.8 to 0.9 gal. The previous link indicated that both were used in 'severe field testing'. In light of the sump volume I wouldn't consider a 10% reduction to be the primary reason for the decreased engine life, instead I'd go along with the authors and place the blame on the extended oil change interval.

Doing some oil change extension versus sump, comparing the 5 qt sump on my Taurus with the 36 qt sump on the N14, it's over 7x as large while the displacement is 4.7x as large. I don't know what the recommended oil change interval was but the 12k interval seemed reasonable considering the power output at 300k miles, while just a bit over 2x on the interval resulted in a dramatic reduction in engine life. It'd be nice to see other wear indicators over the course of the test.

 

[buster]

quote:

---

As has been mentioned before, it's likely there's very little difference in practical engine life between a UOA that shows 6ppm of a given wear metal or contaminate and one that shows 12ppm.

---

I think keeping viscosity in check, insoluables low, watching fuel dilution and any real significant jump in wear is more important. So many different chemistries interacting with different metals in different engines makes it hard to really compare especially when break-in metals are factored it. All the variables have to be monitored.

 

[Gary Allan]

quote:

---

A 10% reduction in sump is 0.8 to 0.9 gal. The previous link indicated that both were used in 'severe field testing'. In light of the sump volume I wouldn't consider a 10% reduction to be the primary reason for the decreased engine life, instead I'd go along with the authors and place the blame on the extended oil change interval.

---

The point I was hoping you could straighten out for me was, "why

". It just seemed like .."well ..let's assure that our point is well taken ...let's exacerbate a few more conditions ..just to be sure ..and while you're at it ...flog the thing." (memories of movie Caligula, "Sire, this guard is drunk! What shall we do with him? ... Give him more wine!!"). I mean I don't necessarily dispute the results ..just wondering about test conditions. I went back to the link looking for an explanation ..but it has timed out about a dozen times ..so I gave up.

I certainly don't have an arguement with "cleaner is better" deal ...and that extended drains with unclean oil in an abusive service will result in increased wear (4 out of 5 doctors who use aspirin as a part of a healthy heart program agee ...)...

 

[Hammer]

quote:

---

Originally posted by 1sttruck:
The Cummins N14 appears to be a 14 liter engine with a 9 gal sump, typically 8 gal for a change. A 10% reduction in sump is 0.8 to 0.9 gal. The previous link indicated that both were used in 'severe field testing'. In light of the sump volume I wouldn't consider a 10% reduction to be the primary reason for the decreased engine life, instead I'd go along with the authors and place the blame on the extended oil change interval.

Doing some oil change extension versus sump, comparing the 5 qt sump on my Taurus with the 36 qt sump on the N14, it's over 7x as large while the displacement is 4.7x as large. I don't know what the recommended oil change interval was but the 12k interval seemed reasonable considering the power output at 300k miles, while just a bit over 2x on the interval resulted in a dramatic reduction in engine life. It'd be nice to see other wear indicators over the course of the test.

---

Just so you know, an average Cummins N14 will take 10 to 10.5 gallons on an oil change. My N14 with Oilguard bypass oil filter will take 11 gallons every oil change.

Hammer

 

[1sttruck]

After not too much thinking...one possibility for using a reduced sump is in simulating sludging. We've seen a lot gas engine pictures with heavy sludging posted at this site, and it's interesting that some of them didn't show up as being a problem in UOAs. I guess that makes sense as any sludging/varnish is by definition not soluable in that oil. We've also seen when other oils are used that high wear metals are indicated, in some cases after two oil changes, until the engine is cleaned and the wear emtals drop to expected levels. A link below discusses varnish/sludging, and notes that UOAs aren't a good tool for detecting the problem.

So far it seems that for increased engine life you're better off using enhanced filtration, something like a bypass filter, and short of that just sticking to shorter oil change intervals. Like the Volvo manual notes use synthetic oil for performance reasons, but since it can't reduce soot in diesel engine oil or smaller wear particles in all oils it shouldn't be the only reason for extending oil change intervals. The $2 question seems to be will UOAs readily distinguish between 'normal' and descreased engine life with extended oil change intervals ? Perhaps a way to indirectly answer the question is to compare UOAs on engines using and not using bypass filters, and assuming that bypass filters will result in increased engine life with similar oil change intervals.

http://www.practicingoilanalysis.com/article_detail.asp?articleid=525&relatedbookgroup=PowerGen

Round Table: Removing Sludge, Carbon and Oxide Insolubles, and Varnish from Industrial Lubricants

Greg - Traditional oil analysis tests cannot detect the molecular changes in hydrocarbons and additives. Nor can traditional tests identify the accumulation of degradation by-products because they are so small. As a result, lubricants that appear to be in excellent condition may still have a high potential to produce varnish and may even cause significant performance problems. FTIR is a useful test to monitor chemical changes on a molecular level and can detect the formation of new molecules that lead to sludge and varnish. Analytical tests such as the ultracentrifuge, gravimetric patch, interfacial tension and colorimetric are sensitive enough to recognize increases in degradation by-products. An easy, on-site test can be conducted by mixing equal parts of the lubricant and petroleum ether and performing a blotter test. Dark brown hues will signify degradation by-products, indicating a varnish potential.

 

[1sttruck]

Another item.... apologies to everyone who feels offended by any of my replies, as there is no ill intent. When I took one of the personality / temperment profiles like Myers-Briggs the results started off with ....'no matter what else you try do not ever go into sales' :^)

 

[Curious Kid]

Gary Allan,

If it hasn't been clarified or determined as yet, the general sense of the graph is that it's misleading.

I scratched my head at first sight to, and concluded:

The new engine was tested with presumably fresh oil.
The engine with 300K miles was tested after having 12K on the oil with apparently no oil loss due to volitility.
The third engine with only 250K miles and 25K on the oil with a 10% decrease in volume apparently due to volitility.

The volitility of the oil, as well as further oil degredation would lead to thickening, which translates to pumping losses and increased viscous drag which ultimatesly results in a decrease in the engines overall output.

Because I have yet to read the article to which the graph is related to, I could be completely off, but as for what the graph is showing me in and of itself and related to what I have thus far come to understand about the nature of engine oils, that is what I have concluded.

 

[1sttruck]

I understood the graph to show power output differences between one engine having received 12k oil changes out to the mileage shown, and the other engine having received 25k oil changes out to the mileage shown.

 

[1sttruck]

The link below is a nice series of UOAs, showing 'dueling filters'. The owner has been using a K&N, initially with Mobil 1, and then added a bypass when switching to Amsoil. The higher iron is assumed to be due to the high silicon, which obviously the Mobil 1 won't help much with. I'd hate to run 15k miles with that kind of a silicon load rate. The bypass filter seems to have helped a lot, the silicon and iron both dropped, but the iron rate is increasing at 7.7k miles compared to the 3.7k mile sample. I think that one also needs to try to determine filter debris, either with particle counts or acid digestion or ? in an attempt to track all wear metals, especially with a bypass filter.

There are different ways to compare UOA results, and I wanted to try to account for sump+additional oil, displacement, and miles on the oil, so I did [(ppm * qts in sump) / displacement in l] / k miles on oil, and ended up with:
sample iron
3000 8.3
4000 6.6
3731 2.1
7762 3.8

It seemed like an easy way to try to normalize the results for comparison.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=002359#000000