About 10,000 miles ago my car too used absolutely zero oil in 4,000 miles (the most I let it go). It was at the same spot on the dipstick as when I changed the oil. Ever since I had my timing chain and tensioner changed, it's been using oil.

Also, I notice my turbo isn't giving me as much power as it did maybe 20-30K miles ago. It kind of grunts at around 3000RPM right after the initial surge at 2750. Occassionally on the highway it will all of the sudden pep up and go like a bat out of hell, then it will die again, and grunt.

My "banjo" fitting is clean as well as the line.