I’ve been using OCI via the Amsoil kits for the last year or so. Was going to inquire about adding PC to my pre purchased Amsoil kits but haven’t had a chance yet.If you're going to be doing PCs, I would suggest using WearCheck instead of Blackstone.
Blackstone has a history of measuring the particle count at only one particle size (probably around 14 or 21 micron), and then extrapolating the results for larger and smaller particles based on what particle size distribution is typical for an engine. More recently, they seem to be doing less extrapolation, but I have more confidence in PCs performed by WearCheck.
It's important to have an accurate particle count for every particle size, since a bypassing filter will have a much larger drop in beta ratio for large particles than it will for small particles, so the PC for large particles will be affected a lot more. The shape of the PC curve should provide a good indication of whether the filter was bypassing.
If you may end up doing multiple PCs to compare different filters, make sure that the recent running conditions of the engine before sampling are similar. I'd suggest idling a warm engine for a set amount of time before shutting it off, and waiting a set amount of time afterwards before taking the sample. It's best not to replace or disturb the air filter at any time, especially shortly before you take a sample.
Still have about 800 miles/4 weeks to go before I change the oil.