Syn 5000/7000 are more resistant to temp, yes. It's base stock oil is PAO aka Group IV oil. The most extreme temp comes from driving at high speed, then suddenly met with traffic jam where the traffic moves extremely slowly. In that situation the cooling system is not efficient.
- the only airflow is air being blown by the radiator fan (because the car is not moving fast enough)
- the air "cooling" the radiator are hot air, coming from the exhaust of cars all around you, stuck in the same traffic jam.
This situation happens everyday in KL, so using such expensive oil do have some merit. Even then it is not required or necessary, just for extra protection. In your case where you rarely have traffic jam, the Syntium 800 or 3000 is good enough.
Why not Syntium 1000? The viscosity is 15W50, which is a thick oil. It may lead to high FC or the engine not working optimally. However Proton makes no warning of its use.
Contrast that to my Honda Accord iVTEC . The manual specifically mentions NOT to use engine oil thicker than 5W40 as it may interfere with the operation of the variable valve timing.
NB: @mengsuan is using Syntium 1000, he is in KL and he finds it just fine. So you might want to try it
Noted and thanks.
I thought Preve Turbo has an auto cut in for cooling if the EO temp is too high.
P/S I am using S1000 after my 1000km service.