My 2005 STI is burning through a quart of oil every 50-100 miles. I have no idea what's causing it. I have no blue smoke, I just had my timing belt service done. My car is mostly stock, just a BOV and catless. Not sure if the car was tuned for catless as I am back firing a lot. I've cleaned my exhaust just to find a black build up on the inside (I'm talking one 20 mile trip and it's thick with black gunk). Replaced cams and PCV valves as well as opened up the downpipe to check the health of the turbo (no shaft play). I took a leak down/ compression test to find cylinder 3 has low compression. I blew my headgasket not too long ago, but sealed it up and haven't had problems since (I drive the car hard). I'm going crazy trying to figure out where I'm burning/ leaking oil. I have yet to clean my engine bay and drive to look for sprays. Can anyone help me?