Whether by condensation, through a deck fill leak, or contamination at the fuel dock, water inevitably finds its way into our diesel tank. How much damage it does over time depends on our tanks design, material, and maintenance regimen. Can fuel additives help? We tested seven diesel additives to determine which is the best at battling tank corrosion: Hammonds Biobor JF, Valvtect Bioguard, Fuel Right, Stanadyne, Sta-Bil Diesel, Star brite Star Tron Enzyme, and Sea Foam.