WD40 Multi Use 420ml is the ubiquitous and iconic maintenance spray that takes its name from the 40 attempts its inventor made to perfect the formula.
Old as the hills, it remains a godsend for everyday jobs such as freeing sticky control cables, driving moisture from electrical contacts or just keeping pesky squirrels off garden hardware (no joke - here's a video).
Just like Coca Cola, WD40 was never fully patented, which allows them to keep the exact formula under wraps. What I can tell you is that it's derived from petroleum distillates that disperse water, gobble gunge n' grime, while leaving behind a thin, protective lubricant film.
This explains how it cures squeaks and keeps chrome looking spotless, but shouldn't be used as an everyday chain lube. But harness its charms to good effect on stubborn fasteners and seatposts and stems on the cusp. But properly seized compenents need the brands' new fast release penetrative spray, which I will review separately.
One of my most surprising WD40 triumphs was a cheap but cheerful rear blinky light with a faulty seal. This had allowed water inside, partially corroding the switch. Removing the back and directing two-second blasts at close range to the affected area while simultaneously toggling its rubberised switch fixed this - good as new in ninety seconds.
Handle with some care though; WD40 will soften car polishes and similar products on contact (placing strips of cardboard beneath bare cable runs before giving them a quick hit solves this) and its highly invasive nature means you'll need to take extra care around rubberised synthetics and even unsealed bearings.
Iconic and extremely versatile corrosion-inhibiting spray. Every toolbox should have some.
road.cc test report
Make and model: WD40 Multi Use
Size tested: n/a
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
"WD-40 lubricates moving parts such as hinges, wheels, rollers, chains, and gears. It protects against rust and corrosion on items like tools, and sporting equipment. It penetrates to free stuck corroded parts like nuts, bolts, valves and locks. It quickly removes adhesives, corrosion and paint. It displaces moisture to restore water flooded equipment such as engines, spark plugs and power tools."
Does exactly what it says on the tin.
Tell us some more about the technical aspects of the product?
Operating Temperature: -10˚ F to 200˚ F
Dielectric Strength: 44,400 - 47,800 Volts
Solubility in Water: Insoluble
For all variations : WD-40 demonstrates none to negligible deleterious effect to plastic, rubber, and metal hard surfaces. This includes Acetal, neoprene/hard rubber, HDPE, PPS Copolymer Polysulfone, Teflon, Viton, steel, galvanized steel, hot dip, electroplated, copper, brass, magnesium, nickel, tin plate, titanium, and zinc.
Performance - WD-40® Multi-Use Product
Nearly all surfaces interact with WD-40 as they would any high grade aliphatic petroleum spirit. Certain types of rubber will swell upon prolonged immersion. Wax polishes and certain wax coatings may be softened by WD-40. Clear polycarbonate and polystyrene may stress craze or crack. Always test surfaces first.
17 um (US)
600-1000 ft2 per gal
Lubricates and Protects
Extreme Pressure Lubrication
Corrosion Protection (Salt Spray)
0.60-0.70 mm at RT
0-20% in 72 hours
Tell us how the product performed overall when used for its designed purpose
Something of an institution, WD40 is an extremely versatile generic spray that does exactly what it says on the tin. However, I'd urge caution around certain materials - rubberised plastics, seals, suspension components etc.
Tell us what you particularly liked about the product
Versatile and extremely effective.
Tell us what you particularly disliked about the product
Can be a little too invasive sometimes.
Did you enjoy using the product? Yes.
Would you consider buying the product? A workshop staple.
Would you recommend the product to a friend? Yes.
About the tester
I usually ride: Rough Stuff Tourer Based around 4130 Univega mtb Frameset My best bike is: 1955 Holdsworth Road Path and several others including cross & traditional road
I've been riding for: Over 20 years I ride: Most days I would class myself as: Experienced
I regularly do the following types of riding: cyclo cross, commuting, touring, fixed/singlespeed, mtb,