White smoke coming out of the turbo and my car is losing power.
It sounds as if your turbo not only has a gasket leaking but that it has also got oil inside of it. Since the turbo is connected to the exhaust it becomes very hot. When oil manages to get inside the turbo it will burn. Burning oil will cause white smoke and it will escape from the turbo wherever it can, in this case the leaking gasket. The loss of power could be related to this as well. If oil gets inside the turbo it will be more difficult to perform correctly. I would recommend having your vehicle looked at by a professional from YourMechanic since the turbo is a vital part of your engines efficiency.