Rust is a metaphorical song about getting older, how the experiences of life add up and eventually rust forms...some say rust is Character - I say it's just scars that show who we are...
As we get older "this steel heart bleeds rust" - and it rumbles as it starts, there are a few dents, it might even seem broken, but it still runs...
Yeah runs..
Having grown up in Saskatchewan, I see an old truck as a great way to tell the story. The little girl with her Dad enjoying the brand new vehicle, falling in love with the truck and even driving it as a teenager.
Eventually it falls into disprepair, and she rescues it - has it towed, fixed back up, and eventually enjoys the ride into the sunset...