The guys at the local welding outfiter recomends ESAB spoolarc 86 wire for welding auto body sheetmetal. This stuff is .030 solid wire that they say has low carbon content which makes it easy to grind and will not rust as fast due to the low carbon. Is this a good choice?

Yes! Use it, it will weld easier too due to the low carbon content. Eastwood sells a similar wire I've used in the past on chop jobs etc.-works great!

Does the low carbon content make a weaker weld? I was thinking of moulding my frame and this would seem like the way to go. Any opinions are appreciated!!

Almost bought a spool on Sat. guy talked me out of it. Said not worth the money and I already had a tab started for close to $300 at the time. Just the basic esab wire for me.