Cheap white vinegar dissolves rust. Pour some into a coffee can and drop in those rusty bolts. Let is sit for a few days sloshing occasionally.
Also works as a gas tank cleaner. Filling it with vinegar and letting it sit for a few days will give you a tank cleaned down to bare metal with lose flakes that can be easily flushed out with a garden hose.Along the same lines…
I recently refurbished a fuel tank that was severly rusted inside. It was so bad that the fuel sending unit components had been totally eaten away! I filled the tank to the top with white vinegar and let it set for 48 hours. The vinegar took it down to the bare metal! All rust gone! I rinsed it, applied etching solution, then Bill Hirsch tank sealant, installed a new fuel sending unit and it worked like a charm! The 10 gallons of white vinegar cost me $11 total!
"foxtrapper" from GT6 Magazine