I have been reading Robert Rapier’s piece on Summer Gasoline over on the main TOD site. Do we have the same sort of seasonal change-over from winter to summer blends as in the US? The temperature difference in winter between, say, Cairns and Cooma, is quite substantial.

I don't know, but I'd suspect not.

We don't really use heating oil, and our petrol stays the same year round, so I can't see why our refineries would ever change output except when new regulations are introduced.