Who told you that the same bloke who sold you the SIP welder lol.
Ive only been welding 27yr so maybe ive been doing it wrong eh?? lol

Pure argon for tig welding ally yeah thats about right.
I wouldn't recommend using a mig to weld ally.
You can get half right results with a spool gun but i wouldn't recommend it.
use the right tools for the right job and you will get the job done right!

Oh yeah and while we are on the subject-
Dont pay attention to the duty cycle???

The duty cycle of the machine is basically how much welding the machine can do on full power without cutting out and you then having to wait twenty minutes for the machine to cool down and reset.
So folks if you want to buy a machine with a low duty cycle and then have to wait 20 minutes between welds.................GO FOR IT lol.

Ps/ the reason theres boat loads of SIP welders on ebey is because people cant get rid of them fast enough after finding out there crap.