Best oil analysis companies?

I use Horizon through Gulf coast filters.

 

I use Blackstone Lab out of Ft. Wayne, Indiana

 

What he said

 

Ya, Blackstone is who I’ve used for over a decade.

 

I use my local Caterpillar dealer, their SOS fluid analysis service. The kit SOS-1 is about $16 which includes a prepaid shipping label. Also, I'd buy their extraction tool, SOS-PUMP if you don't have a port, very nice as the design is such that the oil does not come into contact with anything other than the bottle and the tubing that goes down the dipstick, it's about $27 and well made in a case. Best price I've found.

I have a 2015 Volvo D13 780 with about 850k

SOS Fluid Analysis for Caterpillar Machinery | Peterson Cat