Chemicals that directly attack engine components:
* Acids: Strong acids like sulfuric acid (battery acid) will corrode metals, particularly aluminum and lead-containing alloys. Even weaker acids can cause damage over time.
* Bases (Alkalis): Strong bases like sodium hydroxide (lye) are similarly corrosive.
* Solvents: Many organic solvents (like gasoline, but also others used in cleaning) can dissolve or degrade seals, gaskets, and plastics within the engine. Some can also soften or swell rubber hoses. Brake fluid (which is a glycol-based solvent) is especially damaging to paint and some rubber components.
* Halogens (Chlorine, Bromine, Iodine): These are highly reactive and can cause severe corrosion. While unlikely to be introduced directly, their presence in certain cleaning agents is a concern.
Chemicals that indirectly damage the engine by affecting its operation:
* Water: While water is necessary for cooling, excessive amounts (like from a leak) can cause rust, corrosion, and hydrolock (water in the cylinders preventing piston movement).
* Ethylene Glycol (Antifreeze): While essential for cooling, leaks can be disastrous. It's sweet-tasting and toxic, attracting animals, and it's damaging to many engine components if not contained within the cooling system.
* Fuel Contaminants: Dirty fuel, containing water, sediment, or poor-quality additives, can clog fuel injectors, damage the fuel pump, and lead to poor engine performance and eventual failure.
* Lubricant Contaminants: Contaminated motor oil (e.g., with coolant, fuel, or debris) loses its lubricating properties, leading to increased wear and tear and even catastrophic engine failure.
* Improper Additives: Using the wrong oil additives, or using excessive amounts of any additive, can negatively impact engine performance and lifespan.
Chemicals that can damage the engine's catalytic converter:
* Lead: Lead-containing fuels will severely damage catalytic converters. (Lead-free fuel is mandated in most countries for this reason.)
* Phosphorus: Phosphorus-based compounds in some oils can also poison the catalyst.
* Silicon: Silicone-based compounds from certain sealants or other sources can also degrade catalytic converter performance.
It's crucial to only use fluids and chemicals specifically designed for your vehicle's engine and systems. Always refer to your owner's manual for recommendations and warnings. Introducing any unknown chemical into the engine is risky and can lead to significant damage.
