From a lubrication stand point 10W40 should work fine. I tried doing the same with my Honda 2000. All was well until I tried running it in very cold weather. The Honda shut down via the Low Oil Level Sensor because the cold 10W40 was sticking to the inside walls of the engine hence Low Oil Level alarm. It would start, run for a few seconds, and then stop. I would wait 30 seconds, pull the starter rope, and a few seconds later, it would stop with the Oil Level lite showing. I am back to using 5W30.
LeRoy