I thought I'd share my saga.
I've been going back and forth with Cummins and Spartan for over 2 years on what I presumed to be excessive blowby -- excess pressure spraying the front of the toad and the frame with oil. Cummins finally put a manometer on it to humor me and concluded it was well within spec (11in if I recall.)
It didn't set right with me, I knew there was something else amiss. But to humor them, I installed a jaz can (see below) to catch the blowby. Much to my dismay, I arrived in Myrtle Beach and wouldn't you know, the front of the toad was covered in oil!
When I got home, I picked up some tracer dye from Cummins, put it in and hit it with the UV light. It appears to be blowing oil through the new jaz can breather and through the front crank seal (which would be a real treat to replace from an accessibility standpoint if it came to that.)
I've not gotten any further with it yet. I guess the turbo seal will be first on my list to inspect.
The worst part is, it's 2 years out of warranty now so I'm flying solo!