Preventing rust in gas tank in storage

Good afternoon all.

Between retiring and Covid, I have had more time in the shop, and am taking care of some projects. Several of my bikes need to have their tanks put into long term storage. They are rust free, but I will be draining the petrol and don't want them to rust. Do folks have a preferred treatment to for the inside of the tank in this situation? In the past I have swished a bit of fresh motor oil around before putting the tanks away, but wonder if there is a better way. Thanks for any input.

Cheers

Randy

50/50 mix of oil and thinners, gets to all the corners and spreads quickly, once the thinners evaporates you are left with a thin cost of oil.

Great idea! Do you favor a particular thinning agent?

Randy

Varsol, paint thinner, gasoline. In no particular order.
Shouldn't really matter if you take the appropriate precautions.
Some stink more than others. Some are more flammable.

For winter storage, the simplest procedure is .....

Keep the tank full of stabilized gas

For long term, years? ..... Kommando's method might be improved upon by using Cosmolene thinned down.

Slick

Empty tank, leave outside in sun for 3 days, pour 2 stroke oil in and swirl around to get into every corner.
When reusing, pour half a gallon gas/petrol, splash around, pour out and save for kuse as upper cylinder lubrication.
I don't like leaving tank full of fuel, it becomes a fire risk, hench the importance to let fuel vapor out for 3 days.

Hardwired said:

but wonder if there is a better way

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The suggestions listed above this reply are good. If you couple these suggestions with removing the tank (battery too) and storing both in your house or at least in a temperature stable environment, it doesn't matter a whole lot what the temperature is as long as it is stable and not subject to wide swings of humidity. Put the battery on a maintenance charger. Give your motorcycle hug, cover it up (with a breathable cover); have a glass/stein of your favorite libation.

I have a W650 Kawasaki, what a sweetheart; the owner's manual says to drain the tank and add what amounts to a cup of light weight engine oil, slosh it around; have a hot saki.

Best.

RoadScholar said:

The suggestions listed above this reply are good. If you couple these suggestions with removing the tank (battery too) and storing both in your house or at least in a temperature stable environment, it doesn't matter a whole lot what the temperature is as long as it is stable and not subject to wide swings of humidity. Put the battery on a maintenance charger. Give your motorcycle hug, cover it up (with a breathable cover); have a glass/stein of your favorite libation.

I have a W650 Kawasaki, what a sweetheart; the owner's manual says to drain the tank and add what amounts to a cup of light weight engine oil, slosh it around; have a hot saki.

Best.

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One important thing is once your done with whatever you do (I like oil), wait for a low humidity day and seal the tank. I made the mistake of putting one away on a foggy day one time and the trapped moisture made a mess of it even though I had oiled it well.

OH. Hmm. Low humidity day? In Kernow? Maybe next summer.....maybe....:-(

marshg246 said:

One important thing is once your done with whatever you do (I like oil), wait for a low humidity day and seal the tank. I made the mistake of putting one away on a foggy day one time and the trapped moisture made a mess of it even though I had oiled it well.

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Or, buy a vacum bag for the tank, and one for the bike as well if you are going to store it anywher that is not centrally heated.

Bernhard said:

Or, buy a vacum bag for the tank, and one for the bike as well if you are going to store it anywher that is not centrally heated.

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Plastic vacuum bags are porous, at work I shipped tonnes of steel strip around the world and the worse packing was a plastic bag with the air vacuumed out and the opening tie wrapped tight. What eventually worked best was an aluminised bag vacuumed out and then the opening welded shut with lots of desiccant bags inside the aluminised bag.

The plastic bag being porus and inside a shipping container was every 24 hrs subject to large temperature changes especially near the equator. This set up a pumping action where new moisture laden air was entering daily and the condensing on the cooling steel, next day more moisture laden air arrived repeating the cycle. When the bags were opened at the destination the water poured out. This type of packing had worked fine overland for years inside Europe but failed the first shipment inside a container going through the Suez canal.

Thanks again everyone. I had done a search on the site before posting my question, but what I got back mainly covered over winter storage, or how to remove rust once it forms, not long term storage,
Randy

Onder said:

OH. Hmm. Low humidity day? In Kernow? Maybe next summer.....maybe....:-(

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Ya, the reason I didn't mention a time of year is that I lived in Germany for many years. In Virginia, summer is humid, winter is dry. In Germany and in the parts of Europe I visited, it was the opposite. I suppose if always humid, a desiccant pack and a plastic bag could be used to draw out the moisture before sealing it.

You can also use Bill Hirsch's tank sealer and store the tank dry.

It seems like a splash and slosh of 2 cycle 50:1 gas mix might be an easy and accessible protectant for winter storage. What do you think?

Saber said:

It seems like a splash and slosh of 2 cycle 50:1 gas mix might be an easy and accessible protectant for winter storage. What do you think?

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Bit more oil needed to give a coating of oil, the 50:50 mix I suggested in post 2 does exactly that.

Expanding the scope of this thread, the floats should be drained as well (if putting up for more than a couple of months). And spray the cylinders with a lubricant (kicking over a couple of times)

As an apprentice motor mechanic, I was told a full petrol tank is a trouble free petrol tank. The mean buggers out there that thought running around with a low fuel level in there tanks they were saving the cost of the full fuel level. Yes they were, but those tanks rusted out quite quickly. Why. The theory was that as you use fuel, you sucked in moisture laden air which caused the rusting. I always leave my tanks full as much as possible. Way back in those days, I dont think plastic was used as a fuel container.

New theory. If you completely fill a 20 lire plastic container with petrol, you can leave it out in the sun and the tank wont expand. As soon as you remove a reasonable amount of fuel from the plastic container, then leave it out in the sun, it will expand rapidly. Try it your self and see.

Therefore, this proves that the less room for petrol vapour in your tank, the less the vapour can expand in the tank. It's physics working here.

All the above refers to steel tanks. I remove my f/glass tank and leave it empty when I am not using the bike. [ after all, its my garage queen ]

Slightly off subject I know.

Nothing wrong with using a 50:50 petrol engine oil mix, slosh it around and empty it out. But, dont for get to do that several times a year in case the oil drains to the bottom under gravity.

Personally, as mentioned above, a full steel petrol tank should not give any problems.

Dereck

As the question was about long term storage, I agree with those who would coat the insides with oil of some sort.
In addition, take it to your local pub and bribe them to purge the air in the tank with CO2. Since it is heavier than
air, it forces the air out of the tank. Then seal up the tank and store in a temperature stable location.
It seems to me that any rust forming inside an empty metal tank is flash rust of microscopic thickness and will
readily clean up by a simple soak with a phosphoric acid solution as found in any paint store for priming metal
before painting.

There seems to be a lot of products and chemicals to get rid of the rust. I find the challenge is in rinsing those items out and getting the tank dry from the rinse before she starts rusting again.