5w-20 would be just fine year round. There is no need to go to a thicker oil. 5w-30 though is so similar that you will not notice the difference. Buy which ever is cheaper.

These motors need oil to get to the heads as quick as possible on start up. Which is why a thicker oil is not preferred. These are not old pushrod beasts of past which needed thicker oil.

FWIW I have over 200k on mine using only Motorcraft or Castrol GTX 5w-20 and Motorcraft FL-820s filters.