I cannot explain the exact symptoms, because the leak is usually inside the turbo. The oil goes straight out of the exhaust. I had my leaky turbo diagnosed by the dealer, but I replaced it myself. I believe blow-by will fill the large turbo hose with oil, which will drip out, the turbo oil cooler lines have gaskets that will leak. The return line is especially suspect, because it is "held" on by a couple of o-rings. I know my oil return line leaks a lot. I had two problems with similar symptoms. So diagnosing my problem was a little tricky. I did the turbo first, and under heavy acceleration, my smoke problem subsided. Then I did my valve stem seals, and my heavy smoke problem at idle subsided. That's all I can say. Hopefully a tech will give a little input on diagnosing a leaky turbo.