Permatex 12020-12pk Instant Gas Tank Repair, 1 oz. stick (Pack of 12)

Bonds extremely well when applied as directed, it almost seems to fuse with the metal. However after 1-2 years the material degrades and eventually it just falls right off. I put this on a car that I was fixing up. I didn't even drive the car , it was just sitting there while I was working on other things. Eventually I saw all yellow grass under it and then I realized the patch had fallen off. It left some black goopy residue behind

Ended up replacing the whole tank however as it was very rusty. Great to keep for emergencies or to use for a temporary repair...

I ended up removing the gas tank and putting JB Weld to seal the small welds that were leaking on the bottom.Update Apr 12 2014: Even though I let the JB Weld dry for 24 hours with the tank removed and empty, I have a leak again from the same spot welds on the gas tank. I will get the $250 tank at Autozone.

I had a very small seeping leak on a gas tank welded seam, not a dripping leak, just a area that remained wet. After brushing with a wire brush to remove dirt and undercoating the leak did increase. I did not drain the gas tank(75 gallons) which was full, the seam was half way from top on the side of tank. I followed the directions, cleaned area, removed gas cap from tank, mixed the material to a uniform color, applied the material to a wet with gasoline metal gas tank. It sealed the tank instantly, I only used about 1/4 of the material to seal the leak, spreading it about 1/2" around the area of the leak. 24 hours later I checked for leak, no-nothing leaking. Coated the area with undercoating to prevent rust on the metal(bare from cleaning). I will continue to check this area for leaks in the future but for now ALL is GOOD.

Edit: After about 5 months my leak reappeared. This material had become brittle and I was able to remove it from the tank very easily. Use JB Weld instead.----ORIGINAL REVIEWI bought this because it was an inexpensive, low risk alternative to a more complicated fix to my leaking tank. My expectations were low, but this product works and I recommend it.My motorcycle tank had had a small leak around a hinge bracket welded to the tank due to poor welding workmanship. I prepared this product per the instructions and applied it to the perimeter of the welded bracket. The tank is no longer leaking.This stuff comes as a two part epoxy putty. There is a black inner part and a light gray inner part. Simply cut the amount you need from the ribbon of epoxy and knead it together until you have a uniform gray putty and then apply it.Some use notes:1) This stuff is thick and relatively difficult to mix, but it needs to be mixed well to work. Your fingers may get tired of kneading it.2) This stuff dries fairly quick. From the time I started kneading it until it became too hard to force into the seam was 15-20 minutes. Work in small batches if you have a larger area to bond.3) Apply this stuff with force. The area where my tank was leaking was a seam. I used a plastic screw driver to press the epoxy paste well into the seam.4) Clean the area well. The product adheres to paint, but not to dirt and grime.

I used another tank sealant that failed twice after only a couple days. I emptied the tank, cleaned it and applied sealant, but that particular sealant proved a failure when meeting with gas (Can't name it but my review is on it's page). The hole was 1 mm long and micrometers wide - smaller than a hair so nothing major.PERMATEX WORKED EXACTLY AS EXPECTED. It's been on for months and it shows no sign of coming off or leaking.AN IMPORTANT THING I LEARNED FROM EXPERIENCE: REMOVE YOUR GAS CAP. The back pressure can cause your sealant to fail when setting. I suspect many of the complaints here were due to not reading that fine print. One of my application failures showed this to me. Whoops! Maybe this little but important point should be in bold on the front of the package?

I had a small rust leak at the rear of the tank near the strap (standard problem on Ford f150s). I emptied most of the fuel and raised the truck so any remaining gas was directed away from the leak. I sanded the area and then cleaned the with brake cleaner and rubbing alcohol. I applied the epoxy as directed and even let it sit overnight. Put the tank strapped back on and went to the gas station. The leak was now worse than before. Went home and removed the tank strap and the patch fell right off. This product is supposed to be able to handle gas including a wet surface. Duct tape would have been better. I ordered a new tank and installed but I wasted several days trying to buy some time. Highly disappointed as I have used other permatex products extensively in the past.

Had a small hairline crack on the bottom part of my gas tank of my motorcycle and just emptied out the tank, dried the bottom and applied the gas tank repair. Haven't had an issue with a leak yet and its been 2 months since i applied it.