I like the way blackstone does business. Quick and efficent. I don't like the cost. My past two UOA have been performed by Oil Analyzers (Amsoil's company I think). It took at least 3-4 weeks before I got em back. But at 15 bucks a pop its cheaper than Blackstone.
Last time I was at Napa the counter monkey said that Napa sells UOA kits. The price was 15 bucks (without shipping costs) I forgot the name of the company they used but I might try them out next time I need a UOA.
BTW how much are the butler/caterpillar UOA's??
I did a lab study in 2003?? Posted here somewhere.
Blackstone - is so-so in accuracy. Blackstone was slow for me.
Stinky/Cat - was quick. He was actually good direct service. Particle counts cool. Dunno about acuracy.
OA - is fairly accurate and the web results are quick - mailed reports are slow, though. Price is best for me as mentioned.
ANA - accuracy is lacking.