Has anyone used NAPA's oil analysis service which sends the samples to the Atlanta Lab? I'll be doing my first ever oil analysis, and my local NAPA dealer sells these kits. He's a great parts guy, and says he's had very good luck with these kits. Also, if I don't have the actual sample bottles yet, would it be OK to collect a sample in a medical-grade container the same size as the ones that come with kits? It should be sterile and free of any contamination.