I cannot even count any more how many times I’ve read that nonsense about the limitation of ICP due to the size of wear particles. It seems to me that not many people (including some experts) have ever heard of acid reflux digestion. This is a standard sample prep method in inorganic chemistry. A sample of oil, or wastewater, or soil, or pulp, or cloth or any other material to be tested, is refluxed (on a hot plate or microwaved) with conc. nitric acid for minimum of two hours before measurement. All wear metals got dissolved regardless of their size and analyzed (whether they are 10 or 1000 microns). Every legitimate commercial lab is capable of doing it. For the results of in-service oil to be used for tracking-and-trending, you need to run a baseline with new oil, using the same method. Just like you have to do with any other parameter tests. Unfortunately, for whatever reasons, this method has never been offered to people seeking oil analysis, and their benefits explained.