WD -40 is a penetrating oil the U.S. company WD -40 Company, which is mainly used as rust remover, contact spray, corrosion protection, low lubricant and cleaner.

One of the first applications was the corrosion protection of the Atlas launch vehicle by the company Convair. The first commercial distribution in retail was 1958 in San Diego. The product consists largely of benzine (petroleum ) and mineral oil.


The product was developed in 1953 under the direction of Norm Larsen as a means of water displacement and corrosion protection. The name WD -40 is derived from "Water Displacement perfected on the 40th try" ( German " on the 40th attempt perfected water displacement ").

In Germany and Austria WD -40 and 3-IN -ONE Universal Oil the only products marketed by the company's products. In the U.S. market the WD -40 Company offers a range of cleaning products and lubricants.


The composition differs in the respective safety data sheets.


  • 60-80 % CAS 64742-48-9 (in the broadest sense Petroleum )
  • 1-5 % carbon dioxide CAS 124-38-9 (propellant, not in large containers included)


  • 40-50 % chain-like hydrocarbons CAS 64742-47-8, 64742-48-9, 64742-88-7
  • 15-25 % Petroleum Gas CAS 64742-65-0
  • 12-18 % long-chain hydrocarbons 64742-47-8
  • 2-3 % carbon dioxide CAS 124-38-9
  • <10% non-resin- forming additives


Main applications are cleaning, water resistance and corrosion protection for metals and electrical equipment in service, workshop and household. In workshops, it is also often used to solve rusted screw connections; do so it has to a few hours to act to crawl beneath the grate but sometimes. The lubricating effect of WD -40 on the other hand is relatively small, but sufficient for Bowden cables, squeaky hinges or locks hooking. For the lubrication of threaded spindles or bicycle chains, it is not suitable due to its lack of lubricating effect. Also for weapons cleaning WD -40 is often used in addition to Ballistol.

The loosening of rusted connections by inserting in Petroleum has a long tradition mechanic. WD -40 is the petroleum in purified form and perfumed with Vaselinezusatz to improve the lubrication and protection in a handy spray bottle available. A well-known in German-speaking competitor is Caramba.

More modern rust remover containing molybdenum sulfide ( MoS ). The rust remover and creep properties are in some respects better, but because of the sulphide entry is not the protective effect in the long term. For stubborn rusted connections, the success rate is higher with WD -40, as this affects the long term. Is not possible to rust solution with WD- 40, a separation of the parts can usually be done only by heating the components or by force.