Indeed a compression test is first on the list and I agree that a leaking valve seal is more likely the issue. The car does have a thorough maintenance history of regular oil changes which is why I'm suspecting valve seals more than rings.

I've had the intercooler hoses off and although there was some oil present, it did not seem any worse than I've seen on my 745T. Probably not the best comparison, but a comparison none the less. I'm trying to picture what the "air guide" is. Going to have to look that up. Haven't noticed any stray or spray of oil under the driver's side.

Haven't seen any evidence of cam seal leakage, but haven't really been focused on that either. I probably would have noticed something abnormal when I did the CPS a few months back.

Thanks for the ideas.
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"Differences of opinions should be tolerated, but not if they're too different' - Sharon Craig