It say's on the chainsaw card a gasoline can be discarded if the chainsaw is in danger of breaking. Does the gasoline need to be on the person who's using the chainsaw, or can any random person on the board from whatever distance discard a gasoline to keep it in play?
In this case, there's an implied "this hero". Compare to the Ammo card for how that works. There is, however, room for interpretation -- though I doubt many would say that a hero across the board could discard the gasoline.
I might allow another hero in the same square to discard gasoline. But I'd say that'd probably be a house ruling and not official rules. I'm pretty sure it's just the hero with the chainsaw.