Generally

The tank seal seals all small holes in the tank, as well as seals all rust in the tank.

Tip!

Remove the tank from the car, disassemble the tank sensor. Clean the tank inside, if you have a lot of rust flakes put in a chain and shake around. For best results, clean the tank with e.g. Miracle cleaning KEM-6385, after that you continue to etch the tank with etching tank preparation KEM-6834. then you let the tank dry properly. Plug all but one hole, pour in the tank sealant and shake the tank around to get tank sealant everywhere inside the tank, pour excess tank sealant back into the can. Leave to dry for a day, then repeat the treatment if you have tank sealing left and it seems necessary. (It also works well for diesel tanks).

We found a good description in the magazine Wheels about how to go about sealing the tank. Click on the link and it will open in a new window.

Tank sealing instruction