Originally Posted By: Bigdaddyeasy
I've heard that alot on here but it doesn't make sense. If he did as many uoas with a heavier oil and it showed less iron, it would certainly be relavent. Many organizations trend wear with uoas. Otherwise whats the point here. He could just stop using uoas and just stay at the ocis he's at.
You'll find those organizations trend UOA's so that if an anomaly happens, they can head-off a problem before it becomes a big one. Things like coolant leaks, intake tract leaks, insanely high levels of a particular metal indicating a fragging bearing or camshaft...etc.
And no, an oil that shows lower numbers doesn't mean it is necessarily wearing less. The range of particles sampled by a UOA is very narrow and in the very small size range (well under 10 microns, higher resolution at smaller sizes). Larger particles, which would be more significant, aren't picked up. Also, different oils will have different metals signatures. And the UOA makes no differentiation between chemical chelation and actual abrasive wear so an oil with additives that aggressively bond to the surface (and subsequently releasing some particles into suspension) will show elevated iron, despite the fact that there is no abrasive wear taking place.
But your question is really the salient point. What is the purpose? Well, the point of the tool is to allow the extension of oil change intervals to maximize ROI and to monitor the health of machinery to track for anomalies through extensive trending. This means adhering to a single lubricant (usually) so that the trend is consistent.
The tool is not used as intended by most on this board.
Originally Posted By: Bigdaddyeasy
You can determine about what's a reasonable oci with a particular product, look for issues, or trend wear. In the case of extremely long ocis which I've done in the past with amsoil, you can use them to ensure the oil is still serviceable. It makes sense under that circumstance to uoa. It makes sense for large tractors that hold gallons of oil to uoa to check for serviceability since there's a large expense to dump and refill as well as to help trend wear.
When the term "trend wear" is used with respect to large and expensive machines it does not mean switching between oil brands willy nilly chasing a few ppm of iron or copper. It is to establish a baseline for a machine and to monitor that baseline so that in the future if something shows as being "off" it will stand out from the trend.