My local Honda dealer only had 10w-30 GN4 in stock and I'd really like to change the oil. I know the manual shows 10w-30 as acceptable for less than 85 or so degrees, and here in Maine, that is a pretty average summer day, but it can get much hotter occasionally. I just wanted to get some opinions if I should go for this weight or try to find 10w-40 instead?

Just picked up an '04 RC with 1,600 miles - all stock - and I'd like to continue a few changes of dino before switching to full-synthetic.

If possible I'd try for 10W40 if the weather is going to be over 85 deg.
10W30 would probably work ok, but just to err on the safe side.

Yeah, I think I will return the oil I have and order some 10w-40. Thanks!

30 will be fine but if you've already gotten the 40 then thats even better

10w40 oil is OK, motorcycle or car

10w30 is motorcycle oil only as the car oil will have the extra additives the motorcycle oil doesn't

I ended up returning the Honda GN4 10w-30. The dealer told me that Honda has discontinued their 10w-40 in both the GN4 and the HP4 and will only produce 10w-30. Thought that was sorta strange, but in any case, I picked up Suzuki 10w-40 - all the same specs as the Honda GN4. The bike only has 1,600 miles on it, so I wanted to get at least one more, if not two dino oil changes in before switching to full synthetic. Took me a while to figure out the clips on the fairings, though. All set now - next change will be a breeze!