Thanks Arvid. I have read your post on the subject before. Quite amazing.
I will try the same experiment, but I suspect it is not the same issue. You mention smoke in your post, and I can imagine you would have a fair bit.
I don't see any smoke, just the smell. There is a little smoke haze under high revs and full power, and I suspect the valve seals or guides as the cause of this. But I can idle forever and there is no smoke. Same going down hills.
I just get an aroma that smells like the fumes from the oil filler hole, and it goes away when the car is hot.
Previous cars of interest
1976 Jaguar XJS
1974 Rover 3500
1953 Riley (before they became scarce)