My take is slightly different from everyone here. Even if your car is stock, what is the purpose you want to change to a higher performance oil?
Back when I still had an auto Wira, before I installed a ATF cooler I was on the stock Proton SPIII oil. I used to go Genting a lot and would use gear 2 and 1 a lot downhill. There was one time I managed to overcook the gearoil and once I reached the base of the hill and shifted to "D" it wouldn't go to the overdrive gear and stayed in 2. I stopped by the side of the road to let it cool down for about 15-20 minutes. It started shifting normally after cooling down, after that swapped out the ATF to Diaqueen SPIII. Never had the overheating GB problem after the switch. I personally think better ATF has better heat resistance (viscosity should be the same) and has higher tolerance to take a beating.
If you're just driving casually in town and don't really drag your gears much you don't really need high performance oil especially if there's nothing wrong with your GB. As long as you using original correct spec oil you're fine for everyday puttering around.