Rusty Fuel Tank

[Shazam]

So I've finally gotten around to pulling my fuel tank in my 96. I knew it was going to be rusty, but not this rusty! It's got about a 1/8th to 1/4 of rust/gunk build up on the inside. Anyone know how to get it off? I've been reading around, and a lot of people suggest getting about a 1/4 to 1/2 a foot of metal chain and dropping that inside with some gas, then shaking it around. I feel like I'd be doing that for days though! Any tips? Thanks.

[nordwulf]

There are some videos on Youtube. Solutions range from using rocks to certain chemicals. The one with the chemicals would be my choice.