I can't see where thinner cylinder walls transfer heat less efficiently, in fact it would be quite the opposite. This is why we have thin metal in a radiator. However, the stability of the thin cylinder wall is another question.
Tony, I used to get covered in that PCB filled oil when I helped service reclosers as a summer student. It seems that we survived a lot of things in the good old days ! I also remember working in garages where at the start of a brake job we would pull the drums and clean things off with compressed air creating great clouds of dust filled with asbestos lining remains !
