chev235,
I'm going to go out on the proverbial limb here and say there is no such animal as .023 flux core wire...to small to get the goodies inside.
.035 is common in flux core, and maybe .030, but, as you are seeing, both these wires require more heat and result in burn through on thin panels.
I don't know what welder you have, but there are tag on gas kits available for many small machines. You have two strikes against you if you are a beginner and only have flux core for your body work...pretty tough to do a nice job.
Solid wire with no shielding gas is a notorious swiss cheese producer...maybe that's what is going on!
Stuart
