Oil Recommendation - 2014 Civic SI

[SilverFusion2010]

The 5 or 10w-30 is a bit thicker at operating temp, which helps in several ways. It will handle high speeds without thinning to a dangerous level. There is a slightly thicker oil film holding surfaces apart which helps with protection and the 10w-30 in particular is more shear stable. They are in a sweet spot where they can be blended to meet the 10w rating with almost no VII. Basically a straight 30 that meets 10w pumpability specs. A quality syn 10w-30 is a very tough oil. It won't hurt the engine but if you end up needing warranty work it's a place for the dealer to nitpick. If you choose to stay with 20 go 5w-20 full syn and don't track it until you've done a couple of UOA and have a good idea of what normal is for your engine. Spirited should be fine with 5w-20 if you avoid extended high revs. Basically you don't want to heat the oil so much that it thins out of grade because it's pretty thin already.

 

[oil_film_movies]

What HTHS to run with does depend on which engine we're talking about. Bearing width, pressures are unique to every engine.
That Honda engine does sound like enthusiasts frequently just stick with xw20 that have HTHS=2.6-2.7 values.
Going to an xw30 would only be if you want extra protection that you might not even need.