This might be a dumb one but could not find an answer via Google. I noticed today that the Yanmarengine manual indicates 15W-40 oil for the engine. My Northern Lights genset manual indicates 15-40W. Are these the same? Thanks
Only time I've seen 15-40W written down is when it's been a misprint/mistake.
I still looked it up just to be sure... Google shows a couple of results, one from Amazon for Brookstone 15-40W.
When you look at the image of the container it clearly shows it to be 15W-40.
15W-40 will be correct, be sure to check each engine manufacturer's full specification though.