You sound like a nice guy for loaning your saw to a neighbor. Stop it. You'll probably be sorry. Or be even nicer and go with the saw and do it yourself for him.
Well, on the other hand, a few years ago a friend called me up one morning, frantic for me to drive the 8 miles to his house with my saw. He had been trying to get me to help him cut down a fifty-sixty foot tree that was leaning about 20 degrees, hanging over his bedroom. I could see no way to do this, and the tree was living perfectly fine, so I said it wasn't wise. When I got over there, he had decided to do it anyway and had run a 3/8 inch rope [!!] from about 12 feet up the trunk [!!] across a hundred feet of hillside [!!] to a car parked in his neighbor's drive. Tied it off to the bumper. He'd taken his Homelite with a 14 inch bar and begun cutting. The tree started to go, leaning a lot farther over his house, but didn't pop the rope and the saw ended up falling to the ground and the handle breaking clean off. That's what I arrived to find. There were also workers from the local phone co. and Public Service as the tree now hung not only over his house but over the local utility lines to his house. I was pretty disgusted, but like a moron I said ok I'll help you but your house is not going to skate. He said, yeah, he had already figured on $5,000 to repair the bedroom after we were done. [Notice the "we."] To make a very long day's story short, I went and bought some more cable, put a tall ladder against the tree, made him climb up it and then I attached the end to another car to more triangulate the force on the tree. Scariest thing I've done is when I finished the cut, by which time the local sheriff and news crew were there and waiting to call an ambulance. The sheriff said, well, guys, there ain't no damn way that tree can come down and miss the house, and you are a couple of idiots. [I agreed.] But it came down ok, missed the house by a foot or so, missed the power lines, and I was able to make an exit before the tree did its thing. I told my friend that it was the absolute dumbest thing he'd ever done, and the dumbest thing I'd ever done to come over and help him after I spent six months telling him not to do it. My wife was very impressed. I don't have to explain, I guess, that it was a very negative impression and she told me all about it. And she was correct. The story got around thru the local area and eventually to friends of mine hundreds of miles away...someone sent photos of the tree hanging suspended over the house and me in there cutting.