can you use wd40 to clean car engine

[SanLondon]

No, you should not use WD-40 as a primary cleaner for your car engine. While it can displace moisture and loosen rusted bolts, it is not formulated to safely and effectively dissolve the baked-on grease, oil, and grime found in an engine bay. Using it for this purpose can leave a flammable, slippery residue that may damage rubber hoses and plastic components over time, potentially creating a safety hazard.

WD-40 is primarily a water-displacing penetrant and lubricant, not a degreaser. Its chemical composition is designed to seep into tight spaces and loosen corroded parts, not to break down and emulsify heavy oil deposits for easy rinsing. When sprayed on a hot engine, the propellants can pose a flash fire risk. The oily film it leaves behind acts like a magnet for dust and dirt, leading to a grimy engine bay much faster than if you used a proper cleaner.

For a safe and effective clean, use a dedicated engine degreaser. These products are specifically engineered to cut through automotive grime without harming sensitive components. They are typically biodegradable, have higher flash points for safety, and are designed to be rinsed away completely, leaving no residue.

Comparison of WD-40 vs. Dedicated Engine Degreaser

Feature	WD-40 Multi-Use Product	Dedicated Engine Degreaser
Primary Function	Penetrant, Lubricant, Rust Inhibitor	Dissolving Grease and Oil
Effectiveness on Engine Grime	Low to Moderate	High
Residue After Use	Oily, Attracts Dust	Minimal to None (when rinsed)
Flash Point (Flammability)	Approximately 117°F (47°C)	Typically above 140°F (60°C)
Effect on Rubber/Plastics	Can cause swelling/degradation over time	Generally safe when used as directed
Biodegradability	Low	Often high (many brands)
Cost per Application	~$0.75	~$1.50

The proper cleaning process involves letting the engine cool, covering sensitive parts like the alternator and air intake, applying the degreaser, agitating with a brush, and thoroughly rinsing with low-pressure water. Using the right tool for the job protects your vehicle's longevity and your safety.

[RafaelDella]

Definitely don't. I tried it once on my old truck. It made everything shiny for about a day, but then it just turned into a sticky, dusty mess that was worse than before. It's like putting a band-aid on a dirty cut—it doesn't actually clean anything. You're better off spending a few extra bucks on a can of real engine degreaser from the auto parts store. It's designed for the job and works like a charm without the nasty residue.

[McLeo]

Think of it this way: WD-40 is great for squeaky hinges or freeing a rusty bolt. Your engine bay, however, is covered in tough, baked-on oil and grease. A real degreaser is like strong dish soap, breaking that grime down so it can be washed away. WD-40 just thins it out and smears it around, leaving a film that can actually harm plastic and rubber parts. It's simply the wrong chemical for the task and could lead to expensive repairs down the road.

[VonLouis]

My main concern is safety. WD-40 is flammable, and spraying it around a hot engine compartment is asking for trouble. Even on a cool engine, the residue remains flammable. Furthermore, that slippery film it leaves on hoses and belts can accelerate wear and cause belts to slip. For the health of your engine and your own peace of mind, a product specifically labeled for engine degreasing is the only responsible choice. It's a small investment to avoid big problems.

[Daryl]

As someone who values a well-maintained vehicle, I wouldn't recommend it. While it might seem like a quick fix, using WD-40 to clean your engine is a short-sighted solution. It doesn't effectively remove contaminants; it just disguises them under a temporary sheen. This can make it harder to spot actual fluid leaks later on. A proper clean with a dedicated product allows you to inspect components clearly and ensures no harmful residues are left behind to degrade seals and hoses. Proper maintenance means using the right products.