Can a flux core, gasless MIG welder be used for auto body work? Using a Chicago Electric Flux 125 MIG welder from Harbor ...

To create the weld, a piece of 0.8-mm flux-core welding wire is threaded through the capillary and into the joint, and fed by hand as it’s consumed. It’s awkward and awful, but it works.

Electric types of welding require clean, chemically sound base metals. For older parts restoration, "stick" (SMAW) or "flux-core" would be friendlier forms of electric welding.