Google or visit
http://www.blackstone-labs.com/. This is just one of several labs that are constantly being written about on the various diesel forums. For 22 or 23 dollars they will do an analysis and tell you metals by % in your oil, dilution by diesel, and also the weight of oil you are running (i.e. 15W40 diluted with 5% diesel). Also give you the TBN (the addititives) left in your oil -- these are the wear controllers, etc that make it a CJ vs a CH or other oil spec.
Many diesel drivers are running synthetic oils in their trucks and relying on the oil analysis to determine when to change the oil out. With the additional of the EGR and resultant soot in the oil, some of this is changing. I'm reading a lot of new posts were people are changing the oil much sooner than they used to because the soot is an abrasive in the oil -- This is my own PERSONAL opinion but I don't see how adding soot to the oil can be good for the long term use of the engine. Hopefully we will get the miles out of these that the pre-egr engines were getting and, if by changing oil sooner does that, I'm currently all for it.