Best anti-rust setup for rusting gas tank.

Jan 11, 2007
I dodged a bullet with my Subaru Tribeca for now. I was ready to get rid of it when I thought it had a bad head gasket and a rusty gas tank but the vehicle actually doesn't have a bad head gasket and it was something else.

However, I have a rusty gas tank. Last year, I started smelling gas. I couldn't find the leak so I brought it an indy subaru shop and paid for diagnosis. In the end, they wanted $2600 to replace the Steel gas tank because tons of components need to be dropped to get to it. I have no appetite to replace it at the moment.

What happened was there is a little barb on the gas tank which rusted (or somehow broke) off inside a rubber line that goes to the carbon canister. I cleaned up the area the best that I could and jammed a vacuum fitting into the hole. No more smell or codes and it's been like that for 2 years. Right after doing that, I pressure washed the underside and coated whatever I could reach with rust reformer. The gas tank is impossible to reach and see due to all of the mess around it.

I guess that I am on borrowed time like we all are.

Should I come up with some routine to try and stop the gas tank from rusting at the seams? My first step was to make sure I stopped parking it on grass!

The vehicle is exceptionally rust free besides that area.


I would pressure wash and spray NH Coatings on the tank hoping it will flow around as a liquid. Then it will creep a few inches. NH Coatings seems to creep more that other similar products.

Why is the tank but nothing else rusting? I would expect the tank to be galvanized.
I agree with the NH Oil coating the stuff creeps. It is top quality stuff. A friend of mine got it done at their main office when he bought a new 4Runner. It drips for a day or two and stinks a bit. That is their claim to fame it creeps and gets coverage where you could otherwise never reach.
Depends on the size of the hole as a temporary fix you can get a bar of ivory soap and rub it over the hole and it will patch it for a couple weeks I’ve used that trick on our van which has a small hole in its fuel tank. As for preventing rust get some good undercoating and put on it or something.
Too bad it's not easy to drop the tank - that makes things a lot harder.

I fixed a tank on an old high-mileage Mazda about 20 years ago.

The tank was easy to drop because there was a drain plug for the fuel, and the fuel pump was accessible from above through a hatch under the middle seat.

The tank rusted on top because salty water got splashed up there over the winter, and sat there. The tank was coated with a rubbery undercoating material that had cracked with age, allowing stuff to be trapped in the seams.

I used a drill and fibre wheel to grind off the undercoating, and took the exterior of the tank down to bare metal. Used a putty-like product from POR-15 to fill the rust-caused pinholes from outside. Coated the entire exterior with a black epoxy from POR-15. Used the POR-15 fuel tank sealer on the inside.

Perfect fix, and no problems thereafter.
Thanks everyone! Not sure if it is galvanized. Looks like the tank type was just another one of the existential mistakes of the Tribeca and apparently the Ascent that replaced it!

As far as the NH Coatings go, is that a DIY or do I have to take it somewhere? There are alot of gumballs in this area but I don't see how they could do the job incorrectly save not doing it at all and billing me which wouldn't be far fetched around here.
RP - 342 cosmoline. 2 coats and you're rust proofed for years. Maybe forever. What I like the most about it is the durability and it doesn't attract a lot of sand and grime. It stays clean underneath
You won't be sorry. You haven't sprayed any oil yet right? If you did it has to come off. Don't worry about any surface rust. Just make sure it's clean and dry no oil.
Nope, I have not. Looking forward to this. I did however use rust reformer first. A little, but not overly worried about it.
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