Will oil sampling give a good measure of engine wear?

[JOblenes]

Just a thought on oil sampling. There have been a few threads recently about oil analysis results and wear metals. Lets say that I get an oil centrifuge, and lets assume that it works almost perfectly and removes every little particle including the soot. In this case shouldn't I be centrifuging out my wear metals (which certainly weigh more than soot and should centrifuge better). So while the oil analysis might still give a good indication of the state of the additive packages, acidity, TBN, etc, (the components in solution) the wear metal levels (components in suspension) could be giving a false indication of the actual wear rates in the engine? Any thought?

 

[Gary - K7GLD]

This is an old argument - and the basic reply is, do you want CLEAN, or dirty oil circulating in your engine?



If all you want is "accurate" indication of wear, then remove ALL filters to get the "real" wear analysis you might want - BUT, if you want to actually PROTECT your engine with the best possible filtering - then go for that result with any of several approaches!



Most oil analysis, done by reputable analyzers with proven track records, are for tracking TRENDS in measurable wear metals and other contaminents - and those trends are as easily and accurately indicated either with, or without various filtering accessories installed on the engine.



But, better FILTERING will also provide longer engine life - and isn't that what most would sanely choose, over the "honesty" of totally unfiltered oil?



IF, with a decent bypass filter, my "normal" iron content is analyzed at 8 ppm - but suddenly jumps to 12 ppm, that is EXACTLY the SAME increase as a NON-bypassed engine that will normally show 24 ppm, but suddenly jumps to 36 ppm - biggest real life difference, is that the bypass filtered engine isn't spending most of it's life circulating significantly contaminated oil over precision engine bearings and parts...



Isn't that what most would really prefer?

 

[JOblenes]

Gary,



I understand what you are saying, the reason I posted was after reading this comment from another thread, this is the quote from an oil tester.



"You mentioned you wanted the virgin oil sample to serve as your first sample, so we put them both under the same unit ID. If you actually wanted them to be separate units, just let us know. Your Cummins engine looks great at this point. Wear levels read well below universal averages, which are based on a 6500-mile oil change interval. You ran this oil almost 9000 miles, so you're getting much better wear after more miles--a sign of a great engine. The TBN read 8. 3, lots of active additive left. Note the high viscosity, which isn't hurting anything. Try 10K next. "



How are they rationally concluding that it is a great engine based on wear metals? There could be 3 or 4 oz. of finely ground steel trapped in this guys centrifuge and they wouldn't even know it. I do appreciate the metal is being transported to the filter by the oil and therefore the amount of metal in the oil does have some correlation to the amount collected in the filter and the length of time between oil changes, but still it seems like without them knowing the particulars of your filtering strategy they are taking a shot in the dark.



Just a thought, maybe they should be taking the guts from filter (or sludge from the centrifuge) burning it and analyzing the ash for metals.