Por 15/KBS Rust Seal all work good. Just prep the rust really good, unearth all the bubbly spots, sand, use the appropriate prep chemicals and paint it on. Work quickly, and don't get any on you/your clothes... Get a primer and duplicate spray can of your paint color, and touch it up... Extra points for bondo.. Welding is good if it's a make or break area.. but don't go crazy..

Don't sweat it though. Keep it running, and just don't put a ton of money into it. It'll last longer than you think. But don't become a "Volvo hoarder." Meaning, you've got a nice one, a little rusty, and then buy up a couple more, just to come out with only 1 nice one total. 2 to 3 240's should not = 1 + a boatload of parts.

Each one of those "parts cars" has the potential to become a "daily driver" to someone. Keep what you have rolling, and be considerate. Let someone else have a shot at the ever dwindling supply of 240's out there..

IMHO It's a crime to keep a car made for the snow in a garage all Winter. Spring/Summertime is prefect for rust-poofing and Winter prep. Underbody coating, wax, POR.... Silicone spray/PB Blaster... Tighten before you loosen... I've done it all, and refuse to let my 245 sit-in for a winter... too much fun.