As for the suggestion that there is no such thing as salt air, I don't think that's right. Think of mist and fog -- that's air with small droplets of water. If the water contains dissolved salt, then the air can deposit salt onto a surface like your plane. Just to show this is so, I did a quick google of military websites, and within seconds I found
a test report of "salt air" corrosion for Coast Guard aircraft.
There is no such thing as "salt air." Suspended moisture in a corrosive environment, yes, especially in humid areas where condensation is a factor. Salt, however, does not go into solution in air, and is not carried by air. Spray, mist and other forms of precipitation or suspended moisture, yes. Salt in suspension in the air, and salt air, no. There is no such thing as salt air.
Areas of high humidity, with higher moisture content, tend to show higher rates of certain types of corrosion. Add seaspray, which is not air, that value may be increased, as salt and other electrolytic additives in water do act as agents facilitating greater rates of corrosion. One sees the same thing in areas where a lot of salt is put on the roads for ice in the winter; one could say it's splashed in the air, and vehicles used in those areas do experience increased corrosion, but it's hardly "salt air."
I know there are much better products out there but WD-40 does inhibit corrosion.
Despite claims that WD40 inhibits corrosion, it is untrue. WD40 makes the claim, but does so falsely. WD40 also claims that their product is a lubricant, which is also patently untrue. It is a solvent. It is NOT a lubricant. WD40 stands for Water Displacement, formula 40; it does a fairly poor job of displacing water, forms no significant lasting barrier, does not hold up to water, washes away easily, and does not create a barrier or film that inhibits corrosion, especially salt water. It does okay with fresh water, to a point. It's not long lasting, and it's not great, but better than nothing.. Given that WD40 is a solvent, it does just the opposite of protecting, except for it's limited ability to displace water. It's use can promote corrosion.
WD40 does not cause corrosion, but it can remove oils which do help insulate against corrosion, and allow corrosion at an accelerated rate.
You'll see a few tests below in which WD40, while not outstanding, does a passable job on ferrous metals for relatively short durations. Compared to some products which do claim corrosion protection (but really don't offer any), it does a fair job, but then one might as well use kitchen cooking spray, baby oil, or any number of other lightweight, temporary products.
Some various unscientific tests that use WD40 and other popular products that are frequently used for corrosion prevention on firearms, boats, or simply metal test strips, are below:
An unscientific test of several lubricants and oils rated WD40 as "good" to "very good" in preventing corrosion:
http://www.thegunzone.com/rust.html
A similarly unscientific test with good things to say about WD40:
http://www.gtamotorcycle.com/vbforum/showthread.php?50463-Corrosion-protection-comparison-test
Not so much good to say (worked okay for a few days in fresh water, not at all in a salt water environment):
http://www.thehulltruth.com/sportfishing-charters-forum/123560-test-corrosion-inhibitor-sprays.html
In this particular view, WD40 wasn't very good, but definitely wasn't the worst:
http://www.accuratereloading.com/rustest.html
WD40 did well in this demonstration:
http://www.brownells.com/.aspx/lid=...inic-Knowing-the-Limits-of-Rust-Preventatives
However, for a better view of the results of using WD40, see:
http://www.m4carbine.net/showthread.php?t=103924&page=7
The WD40 version begins at 31:42 in this video; the creator of the video doesn't have anything bad to say about the product; it's not the best, not the worst. Bear in mind that these are rusted nails, not aircraft. Compared to 40 weight motor oil, the WD 40 did worse. We don't smear motor oil on the airplane to prevent corrosion, and there are significantly better products that actually are designed for corrosion prevention available, that we do use.
http://www.youtube.com/watch?v=UNbw0vRjH2s
Bear in mind that in the latter test, the WD40 nail rusted sooner and faster, outperformed up until day 14, and finally rusted completely by day 14. The author of the test suggests it outlasted other products, but that outlasting was by one day. It rusted over a day later than the other products, and many of these "tests" were similiar in nature.
When you're looking for something to protect your aircraft, getting the redneck-bandaid in a can, WD40, as your product of choice is a bad idea.
Also bear in mind that the materials used in the above tests were ferrous, and while that may have some bearing on 4130 steel, it doesn't have as much importance to other types of common corrosion, especially in aluminum alloys, magnesium, and other metals, especially types of corrosion that have other mechanisms of corrosion than straight oxidation. Galvanic and electrolytic corrosion aren't going to be greatly inhibited by WD40, and again, several other actual corrosion inhibitors are available that one is much better advised to use on one's aircraft.
Ok, so what is a good method,for someone who is relocating to a high humidity (i.e. swamp) coastal area of georgia, to help reduce corrosion from becoming an issue. My plane (Arrow) is flown regularly, but will sit for 3 months at a time due to work.
:edit: the plane will be hangared in a relatively new hangar.
Hangaring is a step in the right direction. Climate controlled helps. An aircraft that's regularly cared for and washed with fresh water, kept waxed and which is the subject of frequent attention stands the best chance of avoiding corrosion in general. You could go with a fog treatment of ACF-50 or Corrosion X; this has advantages and disadvantages as discussed.
