Turbo rear seal can cause smoking too, regardless if the charge is hooked up
Is the smoke immediately after starting? or take a few minutes?
Turbo rear seal will take a few minutes
If immediate, i would suspect bad fuel, a cylinder not lighting, coolant in cylinder, or injection pump timing

Now, what do you mean "noticed oil coming out of the fuel" ? Like engine oil out of the fuel line?? Someone may have tried to make it run on used oil like a old detroit, it will smoke from that lol