Rust
This is my kind of topic. When I was in my twenties way back in the dark ages of 8 cylinder engines, I used to travel the country in rust buckets with high mileage engines. My first cross country, Maine to California car was a '59 Impala wagon. The rust got to the point that my feet went through the floor boards. I just pop riveted a piece of sheet metal on the body and kept driving. That year I did two cross country trips in it. In fact I have driven cars that have frames which have split in two and been wired back together. This I don't recommend. If it's any more than body rust, dump the car!!! I have never had a car in New England that saw the engine fail before it rusted out to un-operable. One car I had, a '73 Chevy Impala sedan which was so big I slept comfortably in the back seat, saw a good deal of rust in the back panels but had a solid frame. In Las Vegas a cop stopped me and spent ten minutes walking around the thing with a look of awe. He had never been to the rust belt I quickly surmised. Usually those kinds of cars have the most reliable engines in them in spite of the high mileage, mine did.