It's in every garage, tool shed and project room. Every grandfather keeps it handy when the old chainsaw or snow blower needs to be cleaned. It's been around for over 50 years, has over 2000 uses and over 100,000 members in its own fan club.
WD-40. Chemically, it is a mixture of aliphatic petroleum distillates and petroleum base oil in aerosol. It is a highly flammable material, but that may be the worst determined feature of this veritable wonder product. It should not be breathed in or consumed, but it generally causes no serious exposure side effects. It might dry your skin or cause redness or discomfort in the eyes if exposed.
It will help remove a stuck bolt or lug nut, take tomato stains out of clothing, remove tar from a truck chassis, stop a whole host of squeaks and noises, remove stickers and tape from many places and lubricate almost everything. 
Best of all, and this is what really floored the PR guy, it is 100% non-carcinogenic. None of WD-40's ingredients have been determined to cause cancer. According to its Material Safety Data Sheet:
The components in this mixture have been found to be noncarcinogenic (sic) by NTP, IARC and OSHA
Diet Coke has ingredients that could be cancer causing. WD-40, an industrial solvent, doesn't.
I had a chance to talk with Bill Trumpfheller, the president of Nuffer Smith Tucker Public Relations which handles PR for the WD-40 company. He pointed me to the history of WD- (which stands for Water Displacement, by the way)40.
In 1953, a group of chemists, under the name "Rocket Chemical Company" wanted to create a rust-preventing solvent for industrial use. After 39 failed attempts, they came up with a winner. And what a winner it was, because the original formula used in the 1953 remains unchanged 53 years later.
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Article comments
1 - Howard Dratch
A great product. Just sprayed my folding knife - wicked, it is needed for protection and cutting the stuff my old Swiss Army with all my keys on it won't. It had been immersed recently and was balky. Now it isn't.
Does it really work on body joints? Would it cure my gout or the wrist they set without anaesthetic a few years ago? There was a time that was a theory -- use it for arthritis. I haven't tried but if it isn't carcinogenic...
With WD-40, a Swiss Army knife and a roll of duct tape we can fix the world.
2 - Mohjho
Duct tape if you want it to stick, WD-40 if you want it to slip. All you need.
3 - janu
it seems good, it may work wonders not only in industries but also in a man's day to day life.
it will work for your girlfriends& wives who are troubled by stains on their favourite dresses.
4 - richard
i'm cursed with a bad hip,thanks to a train accident six years ago.it has been getting progressively worse since.last summer i was able to walk five miles twice a day in 55 minutes,now i can barely walk the 900 feet of my train without being in severe pain.with the sciatic nerve acting up as well, life was becomming almost unbearable.that's when i found your site while surfing the net.i was desparate so i decided to give it a try.well i have been using it for seven days now, and to be quite honest i am walking without a limp and even though the pain is still there it is less intense. i'm abloe to walk my train without any discomfort.
5 - oilpan
Wreckon this stuff is as good as a fifth gear...
6 - Bill
WD40 has somehow achieved cult status among do-it-yourselfers. It's a PR triumph but the product doesn't live up to the hype. Mind you, nothing could.
WD40 is a water displacement oil. It evaporates too much to be a good lubricant or rust preventative. It does serve to loosen stuck fasteners, but a real penetrating oil does it better. I like a product called Moovit. It's the best penetrating oil I know.
For rust prevention, you need an oil that contains suspended wax. Usually Lanolin. This creates a rust inhibitor that's good for outdoor tools, salt water gear, etc. Boeshield is good, so is LPS3. Most people swear by whichever product they use, so long as it's an actual rust-preventive barrier-type oil.
As a spray solvent for general cleaning, I imagine WD40 would work but wouldn't have any special advantages. We use Slap Shot in the plant where I work.
These are all different applications and require oils with different properties.
7 - David Bernard Mendez
I am a Vietnam Veteran and I have a lot's of pain in my joints and a friend recomend me the use of WD-40 for them, boy it really work, and I am a diesel mechanic and it is my best tool, so today it is my best medicine. TKS WD-40
8 - Tim Robbins, Sr.
My mother had pain in her knees she was told she would have to have knee replacement surgery she started us WD-40 on her knees she has been using it ever since she can walk with minimum pain also there was a time when she could not use it because of oxygen being used in the home the pain returned. I also was having pain in my joints knee, elbows and wrists since I have been using WD40 my pain has gone down more then with MEDS I am a believer NOW and NO PILLS
9 - treatment
It will help remove a stuck bolt or lug nut, take tomato stains out of clothing, remove tar from a truck chassis, stop a whole host of squeaks and noises, remove stickers and tape from many places and lubricate almost everything.