I know how to do an oil analysis from reading the many posts here and from doing them on C-17's. We called em JOAP or SOAP (Joint or Service Oil Analysis Program). Anyway, my question is why do you have to let the oil flow before taking a sample? I'm sure the reply is something along the lines of "to let the settled contaminants out so that we don't get an unusually high reading". Ok, so if this is the case then aren't we still fooling ourselves? This "settled contamination" is still in our oil when the engine runs. It's just suspended from the agitation and flow from the pump. It's still there regardless. By letting it out before we take a sample, yes we are eliminating false high readings in the analysis, but aren't we inadvertantly giving ourselves false lower readings on the materials that fall from suspension? My idea, if the above is true, would be to somehow take a sample while the engine was running. If you had an accessible external oil line, such as for a bypass filter, then couldn't you install a small valve and, once the engine was up to operating temp, open the valve for a sample? Wouldn't this be the most accurate way to get one because everything that is normally in your oil is still there and not just fallen from suspension and then discarded before a sample? I'm no expert but this would seem to make the most sense to me. Any opinions or comments? Thanks! Mikie BTW, I only ask this because I'm coming up on my first analysis on my '00 Excursion with the Oil Guard bypass filter and Amsoil fill.