That would be good to know that kind of info. There is a guy with a great Z Coupe website that does. Check it out:
Bill's Web Space:2007 BMW M Coupe (E86)

Nope. I just did a one time sample.

Even though I don't have a baseline, my copper was so high, I would say that I was at or beyond the replacement point.

John,

I spoke with a very knowledgable / trusted BMW independent and he said the lifetime ATF BMW uses is complete BS. In the 2001-2003 models the ZF tranny used is a weak point with tranny life of 100-150k. Unless BMW has reinvented the tranny and not told anyone; the lifetime oil bit is a marketing ruse. The metals grind and the shavings need to be emptied with the oil. I guess BMW wagers that 4-5K repair once every 125k miles or so is not enough to cause owners to riot.

Too bad it's not so easy to take a fluid sample from the transmission or transfer box, etc. to get it tested periodically. Ironically the fluid that is easiest to access for testing sample purposes is also the easiest to change.

Agree the copper is high, but if it was from a thrust washer or clutch plate I would have expected the zinc or tin to be high as well. Since it is so high by itself, my guess would be that it is from the cooler, and thus benign. Just an opinion.

There are various sampling kits available if you want to take regular samples. There are tap ports that can be installed, and extraction pumps that are simple to use.

There seems to be a perception that fluid sampling is about the fluid. While the TBN and TAN numbers do give some visibility into the state of the fluid, I have always seen oil sampling as more useful for telling a story about the component in question, much more than the oil itself. By trending wear metals over time, the fluid analysis can be used to catch a failing component prior to failure, and thus support a repair-before-failure maintenance program. In heavy equipment (high $$$) or aircraft applications (safety) there is good reason to do this. In an automotive application, are we really expecting to catch a failing transfer case prior to failure? There are a lot of other indicators that it will be failing, and I suggest that most of us would let it go close to failure in any case. I recall one specific customer who struggled with justifying his oil sampling program, as he looked back at several years worth of samples on 20+ pieces of equipment and concluded that he had in fact rarely been willing to take a machine out of service based solely on the oil sampling results. He saw a benefit in being able to predict when his downtime would occur, but didn't realize a reduction in his maintenance cost.

Oil samples are in and of themselves interesting, but they don't give us much guidance as to how to maintain our vehicles, without trend lines and correlations to failures.

Some good info. In regard to my comment though, my point was that given the almost ridiculous notion of "lifetime fill" I think people would be more apt to change their ATF (and similar fluids) if they were provided with some kind of objective analysis as to the wear rate of the components in question as determine by their fluid, doubly so if those fluid were easily accessible. I know I would.

They have objective analysis on component failures, from their warranty system. They know how long things last, on average. They know how much it costs to fix them when they fail.

Wear rate prediction from fluid analysis is complicated by the complexity of each system. Look at the oil sample posted above. It will be widely assumed that high copper is a problem (it is dissolved in the fluid and not in chunks in this case, unless an LPA showed a high particle count, so I am not sure that it is such a problem, but that is an aside). The copper reading says very little about the fluid, and not much about the transmission. There are alloy thrust washers, so if there were high levels of tin or zinc, it could be a problem. The copper level may just be telling us quite a bit about the cooler. Would anyone put the oil cooler on their PM list, even though this one sample data point suggests it? Probably not. We like to think the transmissions are the problem. And is the cooler really a problem, or just a source of leached copper?

We use scheduled oil analysis in my industry for tracking the source of engine problems, before they become catastrophic failures. Trace metals designed into different bearings/bushings/etc provide signposts to a component that is about to fail, and save searching through the engine for the problem item. That is worthwhile because the cost of downtime in these cases (heavy equipment) is much higher than the cost of analysis. With a vehicle that is as replaceable as a personal car, it is hard to justify the expense. You are more likely to invest in electronic systems that flag the failure after it has happened in order to reduce the diagnostic time, and not even trying to prevent the failure (which is exactly what the car manufacturers have done with the engine electronics).

We have to go back to the fact that oil analysis isn't really about the oil. That is why there is one TAN result, and 12 or 20 or more element tests. It is about the component or system. Pretty much the same concept as a blood pressure reading not being a cause to change your blood, but rather an indicator of a system problem. I am not a doctor, but the analogy seemed apt. All you medical practicioners, please feel free to correct me.

fwiw, trending is also only as good as the sampling procedure as well as the lab itself. Different labs have different mechanisms of testing, which skews results if you flip flop between labs.