There's a lot of nooks and crannies in the tank....I don't think you would ever get all of the sludge out unless you spent waaaaayy too much time cleaning it. I agree, get a new tank...much safer bet....

 

You can weigh the factors (cost, do I want to do it...) Years ago a guy told me about putting pea gravel in a tank with gas and he and a budy shacking the crap out of it to beat the rust loose to clean it. I have done him one better. I used an acid and nuts and bolts to clean severly rusted tanks. Then you can get a tank sealer. The stuff I have used in motorcycle tanks does create a bridge and bond over small spots of rust.

 

I'll talk to my father and see what he wants to do, thanks guys for the info on this. I know bunches about my Cobalt, and I don't know a damn thing about my dads Camaro. Makes me feel ashamed lolol...