Mercedes diesel people, to me!
Getting a whistling/high-pitched metallic sounds for about 30s after a cold start. It rises and let's in lock step with engine rpm changes, then it goes away and doesn't repeat again until the engine is cold. If I wait before driving and hold the engine at about 1000rpm for about 20s, I won't hear the noise.
My initial thought is oil flow. The car has the correct amount, but it might not be circulating quickly enough after startup for the cold weather.
I have about 1500 miles on this 15w30 Delvac, which I thought would be good for year-round. I'm way overdue for a valve adjustment, though, so could that have caused early oil death via too much thinning?
I really need to get my act together with this car. I've been using school as an excuse to ignore it as long as it continues to start and run, but I don't want it to get to a state where it won't run at all, because I've got a feeling that by the time an OM617 is neglected to non-runner status, it will take a lot to bring it back.
Kitten picture for your trouble.