WD-40 has its uses, but it's not the end-all and be-all of lubricants.
It's a putative fix-all that boasts uses ranging from driving moisture from a flooded motor to killing roaches to breaking in baseball gloves to reviving drowned cellphones. Such is its pop-cultural ubiquity that it even co-stars in a well-known handyman apothegm: "If it moves and it shouldn't, you need duct tape. If it doesn't move and it should, you need WD-40." But is that really the case? We put the red-capped classic to the test in five common tasks to see how it held up against other lubes. Now it's time to think twice about our WD-40 overuse.
Breaking the corrosion on a recalcitrant nut is an ego-rattling job (for step-by-step directions, click here) that requires not a lubricant but a penetrating fluid—a very low-viscosity oil. There are a lot of good products to choose from—Kano Kroil, Liquid Wrench, CRC Freeze-Off, BG In-Force—but Bob Cornwell, ASE manager of Medium and Heavy Vehicle Test Development, and a guy who knows oil like Inuits know snow, recommends PB Blaster over everything else, including WD-40. PB Blaster is mostly naphtha and petroleum oil and has a preternatural ability to insinuate its way into minuscule spaces. For best results, apply once with care, wait 10 minutes, then apply and wait again before attempting removal. And if you don't mind a little mixology, try concocting a homemade cocktail of automatic transmission fluid combined 1:1 with acetone, which can be as much as four times—repeat, four times—as effective as any other product.
The "wd" in WD-40 stands for "water dispersal." Reducing moisture in an engine cylinder can certainly help reduce friction and free up compression rings rusted and frozen to the cylinder walls. But a better product for reanimating a stubbornly seized engine is Marvel Mystery Oil, a mixture of naphthenic hydrocarbons and mineral oil. Invented by Burt Pierce after World War I to treat ailing carburetors, it got its name from its founder, who would respond to questions about its composition by saying, coyly, "It's a mystery!" Jacques Gordon, contributing editor at Motor Age, says you just need to remove the spark plugs, squirt some Marvel Mystery Oil directly into the cylinder, leave it overnight, and then try to start it the next morning. Gordon notes that it also has other beneficial qualities: His high-mileage 1952 Packard with noisy lifters was in such disrepair that it wasn't worth rebuilding, so he just put a pint of Marvel Mystery Oil in the gas tank and one in the crank case. The car was instantly quieter, smoother and more powerful. He drove it like that for another year.
Treating a bicycle chain with WD-40 is about as profitable as trying to extinguish a grease fire with a wet haddock. Because its light lubricating properties aren't sufficient to cope with the torque and speed generated by pedaling, WD-40 won't help much. And because water dispersal can degrade heavier existing lubes, it could actually make things worse. Instead, consider a mineral-based oil developed especially for bicycles. Phil Wood Tenacious Oil is a popular choice, but we suggest Finish Line Cross Country, which retains its lubricity even in harsh conditions. Be careful to wipe the excess from the chain to reduce the accumulation of grit, dirt and grime. There are a few other choices, too. You can try a wax-based lubricant, which resists dirt and dust. But wax is an inherently inferior lubricant, and application can be bothersome. Some long-distance cyclists prefer the durable Dumonde Tech BCL Light, which can last up to 1000 miles before reapplication. And, in a pinch, you can use the venerable 3-in-1 Oil.
The best product for metal-to-metal lubrication is lithium grease. It copes well with heavy loads—it's almost universally used on garage doors. It resists water and tolerates temperatures up to 400 degrees F, which means it inhibits corrosion and won't bake off a car-door hinge even in equatorial heat. It is messy, though, so we recommend white lithium grease, which tends not to trace so dramatically. Permatex White Lithium Grease is a popular choice, but Gunk makes one, as do CRC, 3-in-1, LPS, DuPont and others.
What WD-40 lacks in job-specific excellence it makes up for with across-the-board flexibility. In addition to being serviceable in a wide range of tasks (Bob Cornwell uses it to drive moisture from the electrical connectors between trucks and trailers), it is also good at cleaning (Jacques Gordon confirms that it's aces at removing bumper stickers). But its best ability may be discouraging rust. After all, it was first used in the 1950s to prevent corrosion on the Atlas missile. If it's good enough for an , it's good enough for those garden shears.