Lengthy thread on this recently on Cruisers Forum.com, with some heated exchanges both for and against the efficacy. Will leave that debate for another day.
Good article by Steve D. I had a video of him explaining best practices on pulling a sample but I can't find it right now. Suffice to say, cold engine that hasn't been run in a while is worst case. Best case is a tap to draw a sample while running. Normal is to pull a sample from at least an inch off the bottom of oil pan when engine is warm.
https://stevedmarineconsulting.com/o...m_export=print
Peter.
Thread on CF if interested. Took me a while to understand that oil samples are often used to determine when to change the oil which is a good practice, though not exactly practical for typical trawler engines, and even less so for sailboats, the typical on CF.
https://www.cruisersforum.com/forums...d.php?t=231256