CM871 black oily moisture from/under exhaust manifold

[arazdolgin]

Hi guys, seek help here. I have 2010 Kenworth w900 heavy haul with de-mandate CM871 cummins, recently overhauled from previous owner with about 100,000 miles on overhaul. Some blowby fumes coming from oil cap. I drive per boost/pyro gauges only, never overheat or more than 20-25 boost. Around 55 mph. I have egr coolant bypass installed recently. So couple weeks ago found black oily moisture coming around exhaust manifold area. Manifold kind of bs from bpi etc, will change it soon. Do you know what is it? Do I need to start to worry about? Uploaded pictures.