A seal blew. This is just theory but i believe the chra is sealed which keeps the oil and or coolant from leaking into the exhaust or compressor side of the turbo. If oil is in your engine I'd look at the compressor wheel and make sure there's no oil. If the compressor side seals fails the vacuum from the engine can pull the oil from the turbo and into the intake, than your engine and last you exhaust, my assumption is your front seal failed and your sucking the oil into your combustion chamber. At the slow drip rate a turbo is fed oil it might take a little time to see a fluid drop. Once again all a theory, hope this leads you in the right direction.