Depends where you from.....
if you live in my country,spring and summer with temps 40 Celsius,yes yuo should use a 10w-40,15w-40 or 5w-40
OF course if you live in Filadelphia,sure yuo gonna use a 5w-30
About brands,my opinion Mobil 1 or BP Visco7000(maybe only in Europe,this one)