GoodMan , bro
you are reading and getting wrong information by reading their provided manual for using oil .
as per my research 5W30 Grade is for ( -30 degree c to Zero degree ) , yes it is very thin and gives better millage because it is very
smooth to start and operate to engine .
as per weather condition of pakistan ,minimum our requirement grade is 10W30 . which is for ( Zero c to 40 degree c ) .
if i am wrong ,any one can guide me .