In reviewing your April 2006 Editorial and the Prevention Illustrated article from January 2006, I found that I concur with nearly everything written. However, there were a couple of important points left out of each article that your readers should know concerning oil sampling.
The first is that somewhat similar to blood samples, one has to have a base line set of figures to start with. Over many years, blood-sample people have come up with a basic set of parameters for nearly all human blood.
Oil samples from machinery are much the same. Engine samples contain one set of numbers, hydraulic or drive-train samples another. Someone with considerable experience analyzing oil samples can nearly always tell just what compartment a sample originated in, and whether it's a good sample or a bad one.
However, you can increase the accuracy of your oil analysis by taking a "first" sample when your machine is nearly new. Taking early "base-line" samples allows you and your lab to compare results from later on to the early one, and see exactly how each compartment is progressing. I recommend doing this to used machines as well.
Additional benefits from this practice include sometimes finding problems that are occurring as a result of poor assembly at the factory or very early damage from other causes that may be still covered under your new-machine warranty. During my career, I detected several examples of this that saved my company thousands of dollars in repair bills and down time or lost production.
The main benefit is, of course, that having those early numbers will allow you to quickly determine a compartment that is going bad. Once those numbers reach a certain point, it's time to decide what to do, and that decision is often dictated by what's contained in the sample.
I found nearly nobody in the heavy earthmoving or mining industries that ever sampled their bulk oils or oils in tanks aboard a lube truck. This is a big mistake, for those containers can contaminate a whole bunch of machines in just one shift if the bulk lubricants are damaged from water or dirt seeping in through a damaged gasket or seal.
Years ago, some lube-truck manufacturers fabricated bulk containers for mounting on a truck out of just one large tank with the individual compartments separated by a thin bulkhead. Trouble was, over time, those bulkheads flexed enough to crack and start leaking their contents into the next tank over. I've had to deal with new engine oil that was contaminated with coolant or waste oil, gear oil that was damaged by hydraulic oil seepage, and drive-train oil that was ruined by all three. It took a while to figure out just where the contamination was occurring, and it cost us big time.
For large machines and small, if you want to save maintenance and repair money in the long run, there is no substitute for oil-sample analysis. And one important key is, start early.