I just bought an ESAB MIG welder from a friend of mine who was using it for Aluminum. It's the first MIG I have owned and I have a question about the shielding gas I should use. The machine was sold to me with a bottle of pure Argon. I'm going to be welding mostly mild steel, and read somewhere that for arc stability on thinner materials I should be using an Ar, CO2 mix. The other day I was trying to weld 2 pieces of16ga sheet steel with .035 wire and couldn't keep the weld from blowing through the metal. No matter how I adjusted the machine I couldn't get it right. I assume that it is partly my newness with this machine. I was having trouble maintaining an arc at amperages low enough to keep from blowing through. When the settings were low enough to keep the metal from holeing I got almost no penetration, and very tall (rabbit turds) beads. Would switching to a CO2, Ar mix help? I get great welds on ¼" with this current setup.