smoke on 1991 Mercedes-Benz 560SEC

1989 560 my engine will smoke (blue) at high speed ,but vewry little at idle

Asked by for the 1991 Mercedes-Benz 560SEC
Suggest also remove valve covers and check cam oiling system.
1 more answer
Valve stem seals are a common problem. They can be replaced without removing the head but requires some special tools to do the job.