I have a 2009 320 GL Diesel, since i bought the car i noticed the oil is being burned out with no exterior leak, no smoke and the tail pipe is clean. the check engine came on day one when i bought it , yep i was scammed, the stealership recommended to change the catalytic @$5400, without checking the cause of the check engine/catalytic light. I used 0w40 mobile 1 synthetic when i bought it since i noticed the oil is low. I drove around 5000 mile and added 10 quarter. in the beginning it was making 29mpg, I lost power on the highway while getting uphill a lot and start making only 24mpg. i decided to call around and change the oil to 15w40 synthetic valvolin with one quarter of lucas. drove another 1300mile the car lost power a lot and shock a lot. The oil is down by 2 quarter, again called around and I got three opinions. 1) the turbo is bad and need to be changed 2) the intake manifold has accumulated carbon and need to be replaced with the motor in the right side. 3) the piston rings are broken and I need a new engine (the engine starts and the car is derivable, no noise but it is very sluggish when you try to accelerate, and hesitates a bet. No oil coming out of the dip stick, but when i open the oil cover it splashes oil outside ) please help