[ultimateirving]

If the turbo is blown bad enought it will dump oil into the intake, and depending on how that feeds the head, it may not get sucked all the way down to the first 3 cylinders. Take off the intake manifold and inspect that side too to see if the oil has crossed through the head..

You didnt say where you bought the RB from or what tests were done to ensure the rest of the engine was in good order.