I usually use the straight argon with the flux core any way. Just did not know if i would be able to weld sheet metal with non flux core and pure argon. On fenders penetration is not a real issue. They are thin to start with. I will still use the flux core most of the time since it will be on equipment, angle or chanel. I bought the argon to weld aluminum just hoping i could cheat a little on thin sheet metal.

There is no mechanical problem so difficult that it can not be overcome by brute force and ignorance.