quote:That's what I'm trying to tell you. Whether they're in the oil or not ..they aren't detected. The machinery doesn't read much above 5um in size. So it doesn't matter where they are. What does matter is what is there due to them not knocking around and creating more particles ..or disintegrating and making more particles. This we can figure isn't THAT substantial in effect otherwise we would see radically different UOA with bypass equipped engines. What we DO see is radically cleaner oil. I think that you can read this yourself on the Blackstone site. I asked Kristen if they filtered and/or digested their samples like our lab used to do with AA depending on if they wanted "free" elements or "total" elements. She replied that their process reads particles up to about 5um (again, IIRC). They don't digest them. If they digested the samples in Nitric Acid before testing, then you would get results in proportion to the mass weighted average of what's in the oil. Fewer particles (of any size) would give you better UOA since ALL particles would be reduced to the particle size regardless of what their original size was. Any >5um particle would would impact the sample ...while in the normal UOA ..it wouldn't even be read. This further supports the notion that the UOA tells far more about the oil then it can the engine's wear profile. It'll show you that you have a problem ..and someone like Terry can be a guru on interpretation due to his unique insight ..but a bypass is probably a radical upgrade in deposit control more then it is a wear reduction aid. It will, as we have repeatedly seen, extend the useful life of oil. [ July 25, 2006, 11:49 AM: Message edited by: Gary Allan ]
Originally posted by GMorg: If metal containing particles of greater than 5 microns are resident in the bypass filter instead of the oil, then I don't see a way that they can be detected during analysis.