Hey Chi,
I can't remember my password for MSN so can't sign in..
Sounds like your mechanic doesn't know what he's doing.
You bolted up the old turbo without gaskets? That would be why its leaking oil!
If you buy new gaskets from NISSAN, and bolt up the new turbo (cause the old one will blow a shit load of smoke on high boost and has shaft play) everything will run sweet, providing your mechanic knows what he is doing.
I can vouch that the motor never leaked oil. The only oil it did leak was from the power steering pump lines (he crushed them putting the motor in lol).. I hate oil on driveways and blasted mitch when the power steering started to leak.. So if the motor is leaking oil now, I'd check to make sure all bolts are tightened to the correct torque and all gaskets are new.
If your mechanic doesn't know what to do with the dipstick, take it to Top Racing and get them to do it.
Better to be safe then sorry.
Kylie