Just to toss my 2 cents in here.....I've used Blackstone for aircraft engine analysis for many many years. One sample really doesnt mean that much, although of course it can indicate that something major is going on. The trick is to use it on a regular basis and look at the trend. While they normalize it based on oil added during the period and such, its best if you do exactly the same thing each time to eliminate the variables- ie initial fill is the same, added oil is about the same, and operating hours or miles too. The trends over time will show whats going on, and if any issues. Typical in an aircraft you look at Silicon for induction leaks, nickel for valve guides, iron can be cylinder wall corrosion or wear, copper can mean bearings and so on. Since different manufacturers can use different metals for diffferent purposes, its goodness to watch any increasing trends and then link them to materials used in the engine (or transmission). Once you have trends established then you can perhaps do it every other oil change etc.
This reminds me of something else I do on my ZHP that I learned via aviation and thats inspecting the oil filter carefully for particles. In the BMW there is no excuse not to do that, its so easy- no filter cutting!!
And BTW, oil analysis isnt everything, its a good indicator, but there are many documented cases of people finding large metal particles in their filter media, and having good oil analysis and visa versa. Its a good tool but you cant depend on it for everything....
Personally I'll save the oil analysis costs on the car and use that $$ towards the airplane, its getting a lot more expensive to feed these days!
hope thats helpful!!
Tim