WD-40: Utility for cleaning and risks of material degradation

WD-40 functions as a moisture displacer. Its formula consists of a blend of oils and a kerosene-like fluid, delivered under propane pressure. It is effective for freeing seized fasteners, cleaning battery terminals of oxidation, or removing bitumen and adhesive residue from car bodies. While it temporarily silences squeaking hinges and locks, it is not a substitute for a full lubricant service. Material Degradation and Rubber Risks The hydrocarbon structure of the product reacts with rubber that lacks oil and gasoline resistance. Contact with door or hood seals causes the material to swell and lose structural integrity. A critical risk occurs when applying the fluid during the installation of cooling system hoses on pipes; the chemistry disrupts the bond between the rubber and reinforcing fibers, which can lead to hose rupture under pressure. Applying the spray to timing belts or auxiliary drive belts is prohibited. Attempting to stop a belt squeal with WD-40 results in slippage or tooth failure, potentially leading to catastrophic engine damage. Similar risks apply to braking components: brake hoses, master and wheel cylinders, and guide pin boots require only specialized lubricants.