ISX15 CM2250 oil consumption

[gemarsim]

I apologize in advance if there's similar thread.
I have this engine on my 2013 Volvo.
Recently I need to add a gallon of oil every 4 thousand miles in order to stay at the same level. Currently truck is with 675k miles on it.
Emission system has never been altered in any way. No any active fault codes, neither for the engine nor the emissions.
Didn't noticed any power lost or diminished. Engine brake is working great.
the only thing I noticed regens more often since I noticed it is losing oil.Like every 3 hundred miles.
For me it's obvious burned oil clogs the filter.
what's the first step I should do?