......

 

Some of this can depend on where you live. I live in west Texas, so completely draining a metal tank and then hanging it up in a dry place like a garage or building won't hurt it. I see you live in eastern Washington, and it's not really humid there, is it? With ethanol fuels these days, the residue in the tank can attract a little moisture and can cause rust, but that's usually only in more humid climate as a general rule. However, most metal tanks for some years now have a better treatment or composition to resist rust like older tanks did. I guess ethanol fuels brought that about. In the older tanks, they'd rust if you looked at them crosswise.

For the ultimate, cheap protection, get a small container of WD40 that comes in liquid form instead of spray form. Close off the fuel tap, pour in the WD40. Shake and turn that tank every way you can to distribute the liquid. Dump the liquid out and treat it like used oil. Leave the cap open but tape a mesh material over the opening to let it breathe but where spiders and other bugs and debris can't get in the tank. WD40 is a cheap, effective protectant inside the tank. It has both a solvent and protectant makeup in its design.

When you go to use the tank again, just rinse out the tank with a little gasoline.

 

Fogging oil is your friend.

 

I would shy away from WD-40. It's a water displacer, not a protectant.

I used to spray (soak) my snowmobile tracks with WD-40 before storing them (in my garage) for the summer. The following fall, I noticed rust on the track clips... WTF??? From then on, I started using an oil-based coating (Break-Free) on them before storing. No rust the next fall.

So... rather than WD-40, I would recommend putting some straight 30 weight oil in the tank and swishing that around. I would leave the remainder in the tank, and just stuff it full of rags.

 

WD-40 is not just a water displacement chemical. It does have a small amount of oil in the composition to stay behind after the water displacing component and propellant evaporate. It is not the do-all-end-all of spray lubricants by any means, as the small amount of oil it has has a very low viscosity. I don't doubt your results with your snowmobile tracks, as I'm sure that's a pretty challenging application for any protectant. The interior of a metal gas tank only needs a little help to insure against rust during storage.

On Break-Free, many of us in my area who are into firearms found it to leave a fine, gummy residue over time...especially if you carry a semi-automatic pistol on your body. Now this would not be a problem on the snowmobile tracks and in fact would probably be a benefit because it would adhere to the metal components better/longer. Not so great for the smaller, moving parts of a semi-auto. I'm not sure I'd want that residue in the gas tank either.

 

Some type of fogging spray might work just as good or better than wd40. I've used a product ACF-50 on a bare metal frame chromoly at a beach race (Pismo '04 & 05) and can say it worked excellent. Rinsing out goes without saying.

 

No doubt there are tons of chemicals that would work well, as this isn't a critical application. Heck, you just buy the cheapest quart of non-detergent single viscosity motor oil and pour it in and make sure it covers the entire interior. The spray products might be a little more challenging to insure that the entire interior got covered, but all-in-all, I'd go with the cheapest liquid product that will coat and protect the easiest. I'm kind of liking my cheap motor oil suggestion now that I dwell on it more. This isn't rocket science. Go cheap. However, to really stip up the pot, maybe we can get an oil thread going to decide which brand of cheap non-detergent, single viscosity motor oil would be best. I'm going with Walmart.

 

Gear lube; more likely to leave a nice layer of oil in place. Lighter stuff will just run to lowest point. Rinse thoroughly before putting back into service.

 

I had a guy tell me a few weeks ago that his klr manual suggested coating the inside of the tank with diesel before long term storage. I thought that seemed like a good idea. Who wants to be the first to tell me why it isn't??? lol

 

i have a stock 2009+ gas tank with a damaged tumbler (key lock)...if somebody wants it, they can have it for gas tank parts or cap part...the tumbler (key lock) is the only thing damaged...nobody wants it, it's going in the trash...