Now I get it!
Universal averages = everybody's averages for this car, truck, or whatever.
Unit/location averages = your averages on that particular car, truck, or whatever, or
your averages on a particular group/fleet of cars, trucks, or whatevers. (In other words, they're bundling up your UOA history for whatever item it is you're testing and showing it to you.)
It all makes too much sense when you look at it that way. Ouch... my pride.
Alrighty then: if they don't control for oil type or grade when doing the "universal" averages, then, like they said, the add-pack numbers are no good. And you're right about them controlling for mileage, because I remember reading a few reports where they said something like: "the universal averages for this car are shown after 4,658 miles..." But what about everything else?
The universal averages column could
be extremely useful, but only if it's not packed with confounding variables. So say I get my 5.3L GM tested, and the copper is high. I start to panic, but wait... no problem, because I look over and see the universal average for my engine shows high copper as well. I don't have a problem, my engine is just wearing like everyone else’s. Or...
I do a UOA on my 2.4L Acura and the lead is 5ppm. No big deal, what's 5ppm right? But then, I look over and see that 1ppm is the average for this particular engine, meaning that something might be amiss. Probably wouldn't have even been concerned otherwise. Or...
I do a UOA on my 5.4L F-150, and my iron is half of the universal average. Maybe I have a magic bullet routine? Everything else is looking good, now I can possibly extend my OCI, and/or stick with the oil I'm using.
Granted, these results would need to be repeatable, but hopefully you see my point about their utility. Now, that said, the universal averages are also ONLY useful if they aren't confounded by a million different variables. How do I know that the universal averages aren't thrown off by new car owners constantly doing UOAs? Newer cars tend to show more wear metals; is the UA column giving me an accurate comparison basis for my car with 60,000 miles? (Need to control for mileage on automobile). How do I know that Uncle Ted isn't sending in a UOA every 6 months for his Acura that sheds 45ppm of lead? Is that affecting the universal average? (need to control for outliers). How do I know that half the people with my car aren't using the recommended grade? Bulk 10w30 dino instead of the high dollar 0w30 synthetic I used? The two oils in the same engine are going to show different wear patterns (need to control for oil viscosity/type). What about filters? And on and on and on...
The smaller the number of confounding variables, the more useful this piece of information is. The fact that most of the people doing UOAs in the first place are of the BITOGer sort is probably the biggest factor they have on their side. But what if that changes? Add to that the fact that the labs themselves have a certain margin of error, as well do the auto manufactures, as well do the oil manufacturers, as does the sampling technique itself, and with people dumping all sorts of additives in their oil and gas, the “comparison” will be “comparing” apples to oranges after a while.
Sorry for the rant, but I just wish the information was more accurate. UOAs as a rule are only good for establishing general trends in your own engine anyway, but it would be so very nice if there were an accurate norm that you could compare your baby with. My car shows XXX amount of this and that in a trend covering the last three OCIs! Great. You can probably tell even without a universal average that your car is wearing jut fine. But overall, is that a result of your anal-retentive maintenance, or the engine/oil design? This accurate table of universal averages I have shows that most people who run bulk oil for XXX miles, or mid-range XwXX tend to show this kind of wear… is your anal-retentive method cost effective? Instant BITOG in a spreadsheet, just add water. We’ll have a mini “real universal average” with a lot the above mentioned variables controlled for and available for viewing when TomJones76 et al finish their project, but it would be so much better if the UOA companies had done this to begin with. (Or that they would publish the data if they have.)
Oh, and I still don’t know what all the variables they control for are, if anyone knows.
johnsmith, over and out