I would go with helicopterray's suggestion, the other stories here are mainly old wives tales rehashed.
There is a bit to be concerned about that the gearbox vent orifice is not "set up" correctly or has issues.
The vent controls the labyrinth seal airflow at the rear of the compressor.
To set it correctly the plug is drilled one drill size step at a time until it leaks oil and then you go back one size. The idea being that there is enough leakage of air to allow flow of oil through the bearing. If you do have a vent that is one size too big and some oil leaks out of the vent it is not such a big deal.
Where the problem lies is if the vent is too small and does not allow oil to flow through the rear compressor bearing (2) correctly and can actually blow the oil out of the bearing.
It might pay to check this as it could easily lead to bearing failure.
The large amounts of white smoke is NOT normal and your AMT should be able to find a reason for it.