5w=cold crank oil viscosity 30-40 =oil viscosity at optimum temperature (100-150 C engine temp)
5w40 oil would be thicker(more viscous) than 5w30 oil at optimum temperature..5w30 oil will be much quicker in lubricating engine than 5w40..5w40 will be better at lubrication (thicker than 5w30),,though the difference is not much,,and for pakistan 5w30 is too thin..Temperature/climate variation in japan and pakistan is extremely different(here more hot and dusty).and this car was primarily assembled for japan,,i will vouch for 5w40 though but you can use 5w30 aswell.