It will weld aluminized steel but the welds will look like shit and Its tough to keep a good arc going. Bottom line flux core sucks ass. You might want to spring for the mig kit. I have a flux core welder that I converted to mig and the difference is like night and day.

So to answer your question it does weld it but if you are looking for appearance then go with the mig.

Also when using the flux core make sure the wind isnt blowing. Its better in an enclosed area so your shielding flux protects the weld.