Waxoyl is a rust-preventative fluid used first in Europe where it has been used for decades, (primarily for automobiles) and currently distributed in the United States. It is used to prolong the life of steel car chassis and bodywork, by excluding water and air from bare metal and by slowing the progress of existing surface rust using phosphoric acid rust inhibitors.
Thick rust must be removed before application of the fluid. The fluid is a suspension of waxy particles in white spirit, which evaporates after application. Waxoyl is touted amongst European car restorers and enthusiast as being a superior rust mitigation solution in comparison to more prevalent automotive undercoatings because it is a petroleum based product, and creates a thin coating which allows better application and coverage due to product viscosity, and possible penetration of surface imperfections. As such it is a more effective hydrophobic barrier and resists salinity better supposedly as a result of both its physical and chemical properties, which contribute to its reported ability not to "dry out"/ or become brittle and degrade as a result of salt exposure, time, or ultraviolet bombardment. Unlike the more common products which are asphalt/tar like Waxoyl must be applied in warm ambient temperatures or heated in application, or alternatively thinned with white spirit in order to reduce its viscosity. Heating is usually done by placing its metal container in a bucket of hot water. This contributes to its effectiveness by allowing greater penetration of vehicle structural cavities.
The color of the product/solution differs. Waxoyl possesses a gold/amber tone (though black is also available) in solution, and after it is thinned by heating it is sprayable, by a pressure sprayer that pressurises its can, or with a specialist gun powered by a compressor. It can be applied by brush without thinning/heating. It is also available in aerosol cans. Another claim associated with the product is that it is cures to a "self repairing" finish. This is because it does not fully solidify, so that vehicle vibration causes waxoyl to flow into voids in its 'skin'. Waxoyl underseal is bitumen based to resist damage in high impact underbody areas and contains the same anti-rust formulation. It is also designed to remain viscous for extended periods.
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