I'm not too good at MIG welding, and I've never learned much about it. I finally ran out of my last spool of mild steel wire for the little 110 MIG, so I'm going to get a roll of stainless to replace it since 99% of the welding we do is stainless. We don't use the MIG too much anyway, but I figure it might as well be proper when it's used. It's used mostly for tacking up exhaust before TIG, and occasionally for quick exhaust modifications like rotating a flange or shortening a pipe. Anyway, I do sometimes use it for mild steel or mild-stainless welds, so should I be using a 309 filler?

 

just get 308 filler and swap it out if you need to weld MS. changing out a spool of mig wire takes like 5 minutes. you might have to change your gas depending on what you currently have.

 

yes for stainless mig you need a tri mix helium/argon/co2 for proper shielding gas

 

I use argon in both of my tanks, since the MIG tank doubles as a packpurge.

I don't really want to deal with swapping wire out, and like I said I barely do any mild steel with it, but if that's the only option then that's cool, I'll probably end up using stainless for everything.