Volvo Repair: volvo 850 turbo smoking, volvo dealer, volvo 850

Question
I have a 850 turbo '94.  Its purchased 2nd hand so i am not sure what repairs were done on it. You'll have to excuse my ignorance on my limited knowledge on cars. The car is overheating and there is enough oil (or more than) and the coolant is full.  After about 7mins of driving there is smoke (darkish hue) that emits from the car. I would say from the back but i am not sure if its accurate since the car is moving.  At times the smoke seeps into the car from the vents.

Can you give me any indication of what I should check for.

Thank You

Answer
if you have blue dark smoke you are burnig oil from engine or turbo  also if you have to much oil it will smoke car takes 6.3 quart's of oil  make sure  you dont have to much oil .and if the car overheat's you have to check why is it doing it can be anyhing in engine compartment  best take it to volvo dealer  for dignostic   good luck