Free oil is nice and there is nothing wrong with penzzoil, it is a very well additized dino oil. You are going to have to make a judgement call. I would base this on warranty left if any, and the importance of fuel economy. This is a light 40wt so if you fut it with a couple of bottle of 5w20 perfill it would be in the proper range.
If it is out of warranty run it. It will not cause any problems other than slightly reduced fuel economy until tit begins to shear down aftr a thousand of miles or so it will be a 30 weight

so this is not a good candidate for extended drains( the Viscosity improvers will shear and the oil will begin tochange operating viscosity towards that of it's base oil).
If you are under warranty use it in your yard machines, even though it won't be casue of a oil related failure you are setting up an obstacle if anything should happen to your motor under warranty.
Personally I would not feel real good with that particular grade of oil. Any other grade of penzzoil I would take and use for free but the 10w40 is a tough spread for a conventional oil to cover. I would be concerned about the viscosity improvers contributing to deposits on the engines internals.
