Not sure if I agree. This is not a full rebuild. It still had the original cams, crank/bearings, connecting rods/bearings, same oil pump, so only thing new was pistons and rings. The engine had already ran for 1700 miles and that oil had been changed. Iron decreased from 24 to 5ppm, Chromium 1 to 0, Aluminum 4 to 1, and Copper 5 to 1. I have tested engine oil in the break-in period in the past and the ppm were much higher on less time. The only sources for the ISO code of 24 is the contaminated bulk oil, the 10% residual oil from the previous oil change, and the new particulates that were generated from the existing contaminants. The filter seemed to take care of the larger particulates. The 4um particles from the residual oil must have been off the scale to cause 90% of the new oil to rise from 21 to 24.
Originally Posted by PimTac
This was done on a rebuild? To me that skews the particle count tremendously. Even if you say it was clean the engine had to perform some breaking in on the rings etc.