Yes, there are definitely a few threads here on BitoG where this has been shown. I read one the other day where they sent a (well shaken bottle) sample from a single quart of oil to 3 labs, Blackstone being one of them. The other 2 labs had much much higher numbers and were pretty close to each other, whereas Blackstone's were very low. So the guy shook up the same bottle again and sent them another sample and once again, the numbers were very low compared to the other 2 labs. To make it even worse for Blackstone, the numbers the other 2 labs came up with were both pretty close to the amounts the manufacturer claimed they should be at. So it was like a 3 against 1 and Blackstone was just way off.
You could probably dig and find this.... and if I run into it I'll come back and post the thread about it where it was discussed here at BitoG. But the members here basically were saying they would never do a used oil analysis again. There was also a big discussion about Terry Dyson and something about him using Blackstone on some occasions and some other lab too, though I think nobody ever came to a final conclusions. But the result was so bloody awful, I think it pretty much made me to never want to do a used oil analysis again and put a huge cramp in even believing anything from a Blackstone report... which really REALLY sucks for me, as I very much enjoyed that!
I'm sure someone here will link the thread soon, as it had surfaced again recently and I know many people here know of the thread. Also, there's been a couple other threads where something similar has happened. It's very upsetting to me that they are apparently so far off and have such low quality control.