Time involved seems to be more a function of how you send the sample, as Blackstone processes them quickly on arrival. I've sent in my last several samples using FedEx instead of the USPS, for several reasons, including reliability, and not getting interrogated at the counter by a clerk pre-convinced that I'm attempting to wage chemical warfare against him. Since I checked just yesterday when sending my latest sample, the cost of FedEx was $18 and change for either of the reasonable next-day options (not including first thing in the morning delivery, which is like $60) or $7 for second day delivery. The second day option is very attractive, in comparison to the USPS when you consider that you get easy on-line tracking and no hassles.
This time, I decided to splurge and go for next-day (the $18 option). Tracking this morning shows that the package is already well on its way to Blackstone. At the moment, it's in Ft.Wayne being sorted or loaded into the delivery truck. From past experience, I expect to see results by email this afternoon.
As always, you get what you pay for (at least when you use FedEx...).
In contrast, consider the FedEx UOA timeline:
Sunday: took oil sample.
Tuesday: sent via FedEx to Blackstone.
Wed AM: sample arrives at lab.
Wed PM: I receive results by email, posted here.
Of course, I opted for the $18 overnight option. You could save $11, instead paying $7 for two-day service, and add a day to the above times. Candidly, overnight is a bit over the top, but the two day service is so close to the USPS cost that there's just no good reason to use USPS, IMO anyway.
I'm poor myself, I send through USPS. I drop it in the box so I don't have to deal with the clerks. so far no sample lost, but it takes awhile to get there. I bet everyone from here to California looks inside the container.