I'm getting very frustrated! I have a 5 cylinder Audi turbo Diesel that I have rebuilt 3 times now and it still uses too much oil. I just got done with a block that has never been bored, had it bored and put in new oversized pistons and rings. The head was rebuilt and welded at a professional shop 4000 miles ago, and the turbo was rebuilt at Turbo City about 5000 miles ago. After the car warms up good there is no visible smoke coming from the tail pipe, but there is a fair amount of blow-by coming off the valve cover. I have a catch can in line with that tube before it goes through the turbo, and after a 10 mile drive, there is half a quart of oil in it, and another half quart is blown through the intake manifold. This is the same thing that happened with the last block with new 3rd oversize pistons and gapless rings. If it's not the pistons, what are the other possibilities, and how can I easily test for them? I don't have any run-a-way problems with the throttle now, but before this block was installed I had to baby the car back to the shop because it did want to take off excessively when I gave it throttle.