Originally Posted by GTyankee
Australia has temperatures that are much like Afghanistan, 130 - 140F in mid summer
In some areas, yes.
However, on the coastal areas, where something like almost 90 percent of the country's population resides, those type of numbers aren't common.
At least not for any prolonged periods.
And, if my memory serves me right, I believe both Castrol and Penrite [Australian owned] makes a 5W20 grade motor oil available in Australia.