Seriously, the only time a turbo is an issue due to wear is if it's really, really bad... I mean turbine or compressor vanes touching the housing. The more common issue is if the drain is blocked. For one thing the oil flow thru a turbo pretty fast. Second, there is pressure on on both sides that's higher than the pressure in the bearing chamber where the oil is (which is very low because the oil drains so quickly). I interviewed a number of turbo specialists a couple of years ago and they all confirmed this. The main thing to check is the drain... is the oil getting out of the turbo quickly or not? Turbo wear is a possibility, and it deserves being checked, but it's not high on the lost of "likely suspects." I'm not familiar enough with the factory turbo setups to say much of anything specific, but in looking at the pics I have in the Ford manual, it looks like the drain is a cast iron and doubles as the mounting pedestal. I saw a crimped drain hose on a Banks system once that cause a drainage problem but what I would wonder in this case is, if the engine has ever been apart, was the valley pan replaced? If you don't have enough drain holes in that valley pan where the oil drains into it, the oil can back up in the drain systems right up into the turbo and that could cause an oil consumption problem. The NA valley pans don't have enough holes. So, if you know the valley pan has been replaced in recent times... there's a clue.
But start with a compression test and work you way down the list. It could be a combination of ring sealing issue and valve stem seals.
Oh, and all this talk about it being Rotella is garbage. Yeah, use Rotella and use gallons. Switch to DELO (or whatever) and it stops. Right. Get serious people. If, and I say IF, there is a difference in oil consumption between two oils in a particular application, it's tiny to microscopic.
