If your only concern is noise then do what you want I guess, but I'm far more concerned with minimizing the time spent in the regime that contributes most to engine wear - the time between starting the engine and oil supply reaching wear surfaces such as the cam lobes. That's why I run oil with a 5 before the w.
I'll bring up the points again that Australia doesn't have a monopoly on hot weather and that I would question the prevailing oil advice of any country where engines are "old and worn" at 62k miles.
I will try and break it down.
When I talk Australia I talk Mostly Western Australia and outback conditions which can be 50 miles out of the City.
West Australia has 2 seasons only Winter and Summer, 2 weeks ago it was wet and coldish this week its in the100,s it happens that quick, summer temps will last from November until June then all of a sudden it becomes winter.
Other than in the far south western Australia should not have been inhabited but it is too resource and mineral rich, the natives were nomadic and all headed far south for summer.
West Australian weather is like Desert weather but the heat stays all night, its a very dry heat with constant blazing sun with the highest UV index in the world, yesterdays UV index allowed for only 10 mins in the sun, this index is given every radio news break.
West Australian houses outside the city were built years ago with Asbestos sheets inside and outside for a reason.
West Australian Temp is taken in the shade so temps you see are temps in the shade not outside that shade, it has to be taken in the shade because the constant blazing sun affects the equipment, most vehicles are hardly in any shade while running.
A road I built this winter melted yesterday (bled) and the first official day of summer is still 3 days away.
If you park your vehicle in the sun for half an hour the seats are too hot to sit on and you cannot touch the steering wheel that's with seat covers and a steering wheel cover, forget to crank all your windows a few inches put up the reflective shades and you are in trouble.
Before emission controls in the very late 1970,s early 80,s Holden(Chevy) Ford and Valiant (Chrysler) cars easily got 500,000 miles but Australia opened its arms to ever changing Japanese engine tech and smaller engines that wear in our conditions much quicker than the old straight 6,s and V8,s and now any vehicle with over 200,000 Kilometres or 125k miles is classed as worn out and hard to sell. in Japan a vehicle has to have a new engine at 65,000 miles by law!
I have experienced the heat in USA and other parts of the world and West Australian weather is brutal because its so dry and sunny.
I would not even consider using 20W50 in Tasmania Canberra Melbourne or Sydney but West Australia South Australia and the Northern Territory I would and many do and the reason mechanics in these areas recommend above10W30 for high mileage in these area.
Common non synth High Mileage oil for petrol vehicles here is 15W50 and 20W50 same as they use in high performance and racing engines.
