Thanks Jim.
Your answer is similar to the answer I just received from Blackstone Labs.
Here is what I got from them:
Thanks for the e-mail. We measure soot with the insolubles
test, though they aren't exactly the same thing. Insolubles are
actually solids that we get to come out of suspension with a
centrifuge. Soot coats the insolubles tube and the more soot that is present, the more it coats the tube. Soot problems in a diesel engine often coat the insolubles tube so much that we can't even read the insolubles level at the bottom of the tube. If it looks like a soot problem is present, we will talk about it in the comments section.
We don't like to see insolubles read above 0.6% or 0.7% in
diesel engines. There are other tests for soot out there, but we don't do them because we can see soot with the insolubles test.
Let me know if you have any more questions.
