Another "Taxi" Study: Relationship of Engine Bearing Wear and Oil Rheology 872128

[ZeeOSix]

UOAs used by Blackstone and others using the ICP Spectroscopy (ICP = Inductively Coupled Plasma) technique can only detect particles that are in the 5 to 8 micron range and below. So that makes then somewhat insensitive to engine issues that are creating the majority of the wear/damage debris above 5 microns, which is usually the case when real major damage is occurring vs the "normal wear" that is creating the 5u and below wear particles. There are other UOA techiques that can measure a much larger particle size spectrum compared to the ICP technique.

UOA data has to be done on every OCI from day one to effectively monitor the trends (in ppm/miles format), and if there is some major damage going on there will be some kind of trend uptick, but it may not look major on the trend depending on the level of damage. In TiGeo's case, he was also hearing abnormal engine noises and he cut open the oil filter to see what was going on, which is what confirmed something bad was going on.

Source: https://www.machinerylubrication.com/Read/854/oil-analysis-tests

 

[TiGeo]

I am not entirely convinced that a 10ppm spike signifies anything - that is very well within margin of error.

My trend line shows this well. Two new/new-ish turbos? Increase in Fe/Al that falls off to background levels both times. The Al is the key on my recent timing chain tensioner issue...it was bee-boppin' along for 2 years at a nice steady range then a large increase relative to the data...it's quite prominent especially on the ppm/1K miles graph. Not sure how this can be viewed as "margin of error" with as much data as I have. As Zee0Six commented above, mine had a noise so combined noise and UOA said "check filter" which had visible glitter and led to taking it in for repair. My data conclusively show that a 10ppm spike does signify something.