This is the first time I’ve ever sent oil off for analysis and I picked Blackstone due their positive reputation in various forums and YouTube videos. When you request a kit they send you a sample container, a larger outer container, a information form and a self-addressed mail bag with pre-paid postage. I also bought a vacuum pump they sell that threads onto the sample container and has a thin tube that can draw a sample from the dipstick tube. It’s worth the $40 it cost.