Reply to "Welder"

What you want to weld is important. As your friend said, if you're trying to weld high-carbon or 4130 steel, a gas welder won't make strong enough joints; only a gas-shielded MIG or TIG will do. But for mild or low-carbon steel- which most car and most old airplane structures are made of, a gas welder works fine & may be specified by FAA inspectors. As one motorcycle fabricator once said, 'All 4130 gives you is a crash-resistant, unrepairable structure. It won't bend but it sure will break!'

As for stainless, many don't know it but if you're out of argon so the TIG is down, stainless brazes nicely with oxyacetylene. True- you get a brazed joint but in many cases that's plenty strong enough for the job. I altered our Pantera's stainless water pipes a decade ago by brazing (before I found a source of local welding gas); they still hold water!