As a 2003 Honda owner I have followed the 5W-20 debate with some interest. My first inclination was to believe that if Honda specified 5W-20 then of course they must know what they are doing. Then I noticed that many Acuras with the same engine families as the Honda, but running high compression and higher power output (TSX for example) specify 5W-30. Other people's post led me look at some of Honda's non-USA English language web sites. Checking in on the Australia site I find that Honda lists only one "Honda Motor Oil" at: Honda Australia Parts Page This is a 10W-30 SJ oil and appears to be specified for all Hondas in Australia. I very much doubt that Honda makes engines with different internal clearances for different marketplaces, so something else must be the reason for specifying 5W-20 in the US and 10W-30 in Australia. Fuel economy issues and driving conditions come to mind as possible explanations. Perhaps there are others as well. Any comments?