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I have an old 275 gallon fuel oil tank in my basement. It is showing some signs of rust.

Am thinking that a new coat of paint would be a protective measure.

What kind of paint/primer should I use? I read something about Galvanized Metal etching paint. Is this required? I'm not sure if the tank is galvanized, and even if it is would it be needed with the coat that is already on...

There is one coat of paint on it already which I believe is just wall paint.

I have used a bit of steel wool on it already. I concerned now that the wall paint did more harm than good. Do I need to completely remove it?

rusty fuel oil tank

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    Step one, check the tag on the tank and find out exactly how old it is. I think ~25 years is considered a lifetime for these, mostly due to rust from condensate or other water in the bottom of the inside, where you can't do a thing about it. If you wait until it rusts through and starts dripping, it can make an awful mess; or is that me$$? – Ecnerwal Feb 24 '17 at 17:18
  • @Ecnerwal I shall look for a tag, thanks. Don't expect to find one tho! – AllInOne Feb 24 '17 at 17:27
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    If there's no tag, you can pretty much assume it's old enough that replacement should be high on your list of options. Most I've seen are in the top/middle area of the tank, and should list date, maker, and test pressure, or something similar. Often stamped metal. Might include a UL symbol. – Ecnerwal Feb 24 '17 at 17:29
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    To back up @Ecnerwal, when I was a teen, our fuel oil tank leaked and needed cleaned up. All the clothing I wore during the cleanup had to thrown away and I smelled like fuel oil for weeks and the basement for months. :( – UnhandledExcepSean Feb 24 '17 at 19:25
  • I would ask, how often in winter do you need to fill the oil tank and how much oil you use during the winter? If the answer is less than 550 gallons per winter, I would opt for 2 new tanks so you could have all your oil delivered in August when fuel oil is the cheapest. You could also bury a 1000 gallon tank. – d.george Feb 25 '17 at 10:32
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It's possible to measure the thickness of metal with ultrasound. Since water is heavier than oil, but has water vapor, you only need to check the bottom and top of the tank.

Yes, the wall paint is useless and in the way of proper paint prep. Despite what certain TV ads say, you can't really paint over rust.

The ideal coating is media blast to near white metal, then MIL-PRF-26915 primer, epoxy primer which can accommodate a variety of topcoats, then a 2-part LPU coating. We can whittle that down to something achievable.

I have had very good luck with the following:

  • Create very dry conditions, long enough to thoroughly remove moisture from rusty areas, i.e. Park a dehumidifier there for a couple of days.
  • Wire brush, sand etc. down as clean as possible. Any paint stripper should easily take the latex paint off.
  • 2-cloth wipedown with common paint thinner to remove contaminants
  • Rustoleum rusty metal primer - though cheap, it performs surprisingly well over that last little bit of rust you can't get off without blasting. Stir the can very thoroughly, the sediments at the bottom are your friend.
  • couple days to dry; quick swiff-sand with a scotchbrite pad to remove gloss
  • rustoleum is not a final topcoat. Overcoat with ideally a decent 2-part epoxy primer or paint.

If you don't use a 2-part epoxy, then finish it up with an alkyd (oil) topcoat.

If you do use a 2-part epoxy primer, you're done if the tank is shielded from the sun. UV light from sunlight will wreck epoxy. So you'll need to swiff-sand again and topcoat with, well, you can topcoat epoxy with pretty much anything, even that wall paint. Maintain the topcoat, don't let the epoxy primer be exposed to UV.

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The best solution unless you could empty the tank and inspect the inside for corrosion is to replace it! First reason is security of you and your family if it leaks, not just loss of property but also loss of your loved ones lives. Second is your insurance provider will mandate that you replace the oil tank with the new double tank design that costs $$ however it protects you and your family. As noted painting the outside does not solve corrosion inside, as well some of these rust paints are hazardous to your health because of the ingredients to prevent corrosion, many are only available in commercial enterprises due tom this, the read oxide Rustoleum is one of these, sanding makes dust that is hazardous. It might also be time to look at a new heating unit as they have vastly improved and more efficient.

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