Pluses for Oil Analyzers:
1) speedy turnaround. I use the UPS prepaid kits and my sample gets delivered within 2 days and OA gets me results within 2 days.
2) TBN is built into the cost
3) they also include oxidation and nitration values
4) they use gas chromatography for fuel dilution, which is most accurate
Minuses for OA:
1) total cost is higher than Blackstone ($48.78 vs $35-$45) if you're buying one kit at a time. Cost goes down the more kits you buy at once. Best cost per kit is at 3 kits or more at a time ($38.79 per). This is because they charge for shipping and tax, neither of which Blackstone charges for.
2) less user friendly, both with their web interface and with customer service.
3) if you want to save money and buy multiple kits, you may not use them all right away. This increases the chance that you might misplace/lose the kits before you can use them.
Pluses for Blackstone:
1) One flat cost of $35 without TBN or $45 with TBN. Shipping included and no tax on top.
2) Universal Averages included with your engine type, so you can see normal values for your engine to compare your results to.
3) Super easy web interface and great customer service.
Minuses for Blackstone:
1) USPS shipping is slower. Typically takes 4-5 days for delivery for me vs. 2 days for UPS (shipping similar distances).
2) Analysis is very slow. Expect to wait 2 weeks for your results once they receive your sample.
3) they derive fuel dilution from flashpoint and viscosity loss which is much less accurate than gas chromatography.
4) oxidation and nitration results are not included in the cost.
5) their viscosity results are sometimes lower than expected, bringing into question their accuracy.
Personally, I like Blackstone's Universal Averages a lot. But I like OA for everything else. So I will use BS once for a vehicle to get the UA, then use OA for future samples on the same vehicle. I don't like having to spend over $116 at a time to get the best deal with OA, and don't like having to keep track of my kits until I can use them up, but OA has too many other advantages to not use them over BS in my opinion.
