oo oo i looked this up somewhere once. the lower number is its cold viscosity while the higher number is its warm one. basically 5w30 is better for colder weather since its first number is lower, while 10w30 can be used in warmer weather. But the 5w30 has a larger distance and therefore uses more modifiers to let it have that wide of a range and less oil basically it wouldn't matter in a well designed and maintained honda, but I guess if it starts to over heat or gets left in too long 5w30 has a bigger chance of degrading and causing carbon deposits so 10w30 is a good choice if your not in snowy weather or something. But like I said with regular oil changes and maintenance 5w30 works just fine.
Yes this is correct.
The first number is cold viscosity and second is operating temp viscosity.
and there are several modifiers in 5w 30 to get it to behave as such which means it can degrade quicker and all that.
But that is with conventional oil.
Now enter synthetic oils. They are basically formulated a certain way reducing the modifiers needed.
So running a 0W 30 wouldn't be out of the question either since the cold start up will be better and the Oper temp will be the same and you don't have to worry about it breaking down the way "dino" oil would.
But then, synthetic oils aren't all FULLY synthetic. I think there are only 2 or 3 oils out there that are FULLY synthetic. I think amsoil and royal purple are fully synthetic.
Here is a link that if you have time, explains what MistahJuice and I were trying to explain.
http://www.supramania.com/aehaas/
In the end this isn't a high performance car and was designed in that manner. Pretty much any oil you use with decent filter will give you many years of happiness with proper interval in changes.