I have had a new Honda since 1980...or an Accura...
Presently Honda 2010 Accord V-6 iVtec/VCM SE/LX NAV.
You will not notice a difference in performance using either 5W-20 or 5W-30.
Have a 2008 CRV too 4-cyl...use Quaker State semi-syn 5w-20...OCM pops up about 7,000 miles...have not even a remote thought of changing.
...now I do know that if you use 0W-30 GC or a 0W-40...the car engine needs to warm up and get to temperature...and signals that the engine does like a thinner oil..
..why fight city hall...5W-20,,,