The owner's manual states either 30 grade, 10w-30, or 5w-30. SJ or later (which is pretty wide for the spec range). There have been a LOT of lube improvements since SJ.
Yep. I'm outside of the temperature range for 30 grade though.
I, too, don't understand how you can get all the other grades, but not 10w-30. But whatever ...
Me too (at the time). I'd looked at dozens and dozens of product listing for a number of manufacturers ... couldn't find a 10W-30 anywhere ... until ... (of all things) I found Honda 10W-30 at a marine dealer (and grabbed a couple of litres). So "problem solved" for now.
It sounds to me like this pretty much never gets used, and if it were used, it would only be for a temporary time perhaps up to several hours. In that case, frankly, the oil grade probably does not matter as long as you're "close to" the preferred spec. In fact, if it does not get too cold there, why not just use a mono-30 grade if you cannot get multi-grade 10w-30? The only real risk with a thinner lube is that may experience some volatility a tiny fraction more than a thicker lube, but frankly if the unit is only going to run infrequently, you'll end up changing oil long before the LOS function would intervene anyway.
We just don't know. It's only got 36 hours on it to date -- but it was only a few years ago that we had some massive earthquakes; many were without power for many weeks. I'm trying to be prepared for these types of things. By my way of thinking (right or wrong) there's probably one oil type/grade that'll provide the best protection - whilst others may "do the job", I fear accelerated wear if I get the wrong one. I'm pretty familiar with 15W50 that's used in my motorbike and I was quite surprised at how different the 10W30 was when I put it into the first generator. And that's my problem; I get so much conflicting advice, and I don't know enough to sort the wheat from the chaff.
Side note: How old is your genny? If it's older, have you changed the timing belt? That's probably a far greater risk of stopping your Honda than what oil grade you choose. The timing belt in these units is a wet-belt design. Age and oil impregnation are an issue with this design.
It's exactly 10 years old. No - I've never looked or thought about the timing belt. I've found YouTube videos on changing them, but nothing on recommended change interval (including the manual) what are your thoughts on the interval (I'd have to send it away to be done -- too old for that kind of project).