[proticus]

when you said that the coolant was black, you didn't mention how long it had been since your last coolant flush. a little automotive 101 here. white smoke usually means (if it's not water condensation on a cold day) that coolant is entering the combustion chamber. and the blue smoke would indicate oil entering the combustion chamber. if it is only smoking when you start the car, it is most likely worn valve seals. if it is continual while you are driving, it is most likely worn piston rings, or worn cylinders. For your sake, i'm hoping it's the valve seals.