I just bought a new Honda self-propelled mower. It came with a small bottle of Honda 10w30 that I put in it. It recommends its first oil change after 5 hours. It recommends 10w30 which isn't a problem. However, I have quite a few quarts of Mobil 1 10w40 that I picked up on clearance for an older vehicle that I no longer have. I also used it in an ancient Briggs & Stratton mower I no longer have. I don't want to put it in my newer vehicles but was thinking it might work ok in this Honda mower application. Of course, I don't want to damage my new Honda mower. Thoughts? If the consensus is that it's no good for my small engine I can just use it for top up oil or use a quart here and there on my vehicles mixed with mostly 5w30.