I use Blackstone for each car (with a base line when new) - I'm only looking to make sure the numbers are close to the last sample.. IE: looking to be proactive in looking for problems.
So, I'm up to 171K on my 99 Nissan Altima - 65K on my 2000 F350 and 67K on my 04 Crown Vic (not including my Kubota, ATV, Cobra and Company cars).
Blackstone is only $22 per sample and quick with the reports. Unless someone can offer a better suggestion for
oil samples, I'll stay with Blackstone!