2013 freightliner cascadia dd13 turbo replacement

I replaced this turbo 3 months ago because oil was getting to that pipe. It’s doing the same thing again . Any suggestions on what can it be? What would happen if the turbo is not mounted tight enough to the 4 bolts I believe that connects to the manifold that keeps the turbo on. If that’s not tight enough would that cost a leak of oil? I don’t know what to do . My truck is deleted pdf def and erg. I ran it deleted for 7 months with no problems then I changed the turbo and 3 months since that it’s doing that again need help asap