A while ago, I had to remove the charge air pipe from the turbo, as part of a bush replacement job. I noticed that the inner surface of the pipe had an oily residue on it. Is it likely to be normal oil residue that has been dumped into the compressor by the breather system, or am I looking at a leaky compressor shaft seal?
Condition wise: oil consumption is not excessive, and there is no exhaust smoke. The turbo pulls very well - infact, just a few days ago my factory spec. car outdragged an impreza turbo, complete with enormous exhaust and all the trimmings! Nevertheless, I have been slightly worried about the oil, as I am aware that it has to pass through the intercooler and valves before it is burnt. Cause for concern or nothing to worry about?