Have you got empirical evidence using recommended cheap 5w30 compared to holy Allah wala 5w50?
corolla are cheap economy cars, it makes no sense to run them with a lube that causes the owner to spend more in fuel and maintenance.
I have another example - Mazda MZR when run on 5w30 vs 5w20 renders a bit worse fuel economy but only seen over 10,000 miles average. Mazda has printed 5w20 on the cap and in the book it recommends semisynthetic (due to the oil ring design on it)
using 5w20 gives best mileage, startup and life. Some people thinking they have conquered earth like Alexander have put diesel 5w40 in it.. Yes it runs quieter, but they pay in fuel wastage and struggling behaviour of engine. (same people assumed that it was noisy,, forgetting that the noise they were hearing is characteristic noise of that engine).
meanwhile - I can show you GM 3.4 V6, it takes 5w30 (cheapest of the cheap type) - and is so quiet at idle that you will probably want to spin the key again. Its due to the engine design, its an iron block 60 degree V6 with cam in block design.
