I installed a provent before the new intercooler was installed and I've noticed a light film of oil in the IC since so I guess it's either leftovers or a very very small amount still gets through.
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My provent went in, together with the new intercooler and it still got mist on the inside. Not as much as before, though but oil is still present.
I have long had a suspicion my turbo is not quiet right due to this mechanical, wind up noise, which is in sync with the spool up sound. I hope i'm wrong.