not weird, actually every engine is almost same....not only honda's using w30, but most of K-car r using the same grade as well...weird thing bout honda's, seems like honda engines thrive on 30w oils both on cars and bikes. If even use a 40w oil, it wud be noticably heavier on the power. Hmmm........well, its true for bikes, i dun reli know bout cars aktuali, hahahahaaa
wat i know is, most of malaysian using w40 for their non-turbo car....thats wat i saw... they claimed that using thing oil the engine or the car will 'kaboom'.....
u can using thinner oil if ur engine is in very well condition...