Install a new oil drain tube
Always replace the oil drain line/tube when replacing a turbocharger: If the oil return line from the turbocharger is partially clogged or blocked, the oil will back pressure into the turbocharger and seep past the seals, the oil will enter the intake and find its way into the combustion chamber. This causes excessive oil consumption and smoke. When a large volume of oil enters the combustion chamber this has been known to cause an out-of-control engine over speed [the oil is being consumed as fuel].
Prime it
Always prime the oil inlet on a turbocharger for the initial start: After making sure the turbo fits properly, remove the turbocharger and fill the oil inlet with fresh oil. The shaft bearings inside the turbo must be lubricated prior to start-up to avoid premature failure. Starting an engine with no initial lubrication on a turbo can be disastrous.