Hi,
I have a US (American) 2005 Accord LX Auto 4 cyl. My uncle has also an American made 2000 Accord LX Manual (bought in Europe from Honda dealer - it is the actual accord exported from US to Europe - the only difference is the engine is not 2.4 - it is 2.0 liter).

Now, in my uncle's Honda manual it says oil should be changed every 10k miles and that he can use 5-30, 10-40 oils.

My manual (05 Accord LX) says use 5W-20 oil. I have a feeling that the only reason they want us to use 5W-20 in the US is to get a better fuel economy. However, (even though I always use Mobil 1 synthetic) I feel that my car engine will be much better protected with 5W-30 as opposed to 5W-20 oils.

My question is - can I use in 05 Accord 5W-30 or will it (besides fuel economy) affect the engine in negative way at all? What about in the summer? Can I use 10W-40?

Thx