Where Not to Use WD40: 19 Places That May Surprise You!

The lubricant WD-40 is a popular product with lots of great uses. Most of us have a can or two on the RV or around the house and use it for lots of things. (It’s well-known for removing grease and adhesives, for example). But what you may not know is where NOT to use WD-40.

There are many situations where a spray of WD-40 not only isn’t your best option but could actually be harmful. Rather than being a quick solution, it can create a whole new problem… or even cause damage.

Today we’re listing out 19 places where WD-40 isn’t the best choice, and why. That includes some places you should never use WD-40. Of course, we’ll provide alternative choices better suited to a particular job.

What Is WD-40?

As we noted in detail in our post “21 WD 40 Uses on Cars that You May Find Useful for Your RV!“, WD-40 is actually a brand name.

WD-40 is an American company based in San Diego, California. “WD-40” is also the trademark of the popular product we’ve all used for decades. according to the lab book used by the chemist who developed it, WD-40 stands for “Water Displacement – 40th formula.”

WD-40’s formula remains a secret to this day. In fact, it wasn’t patented back in the 50s to avoid having to disclose the formula. (Interestingly, the European and Australian formulations are different.)

According to the Material Safety Data Sheet information, WD-40 includes the following content based on its CAS numbers:

• 45–50% low vapor pressure aliphatic hydrocarbon (isoparaffin)
• <35% petroleum base oil (non-hazardous heavy paraffin)
• <25% aliphatic hydrocarbons (same CAS number as the first item, but flammable)
• 2–3% carbon dioxide (propellant)

As you can see, WD-40 does contain a petroleum-based oil. And although many of us have used it as a lubricant, it’s not the best in all situations. In some instances, it’s not a good idea to use the original WD-40 formula at all.

Keep in mind that the “WD” stands for water displacement. This means that it’s designed to move water away, often from metals that have been exposed to moisture.

WD40 has long been touted as a fix-all, cure-all type of product. In fact, DIY lore has long held that most repairs can be made with a can of WD40 and a roll of duct tape (and a hammer?) 😂 WD-40 is great for lots of things, but it isn’t always the best, or even the right, choice. And sometimes, it’s one of the worst things you could use.

Where NOT to Use WD40

First, we want to make clear that throughout this post we’re referring to the original formula of WD-40 – the standard, multi-use WD-40 that’s been around for years and years.

We’re NOT referring to the specialized products they’ve come out with over the years that are more focused (or completely different) formulations. Clearly, the company understands that the original formula is not a cure-all, and they’ve developed other, more specific, formulations for various uses.

For example, while WD40 is a lubricant, it’s not necessarily a good lubricant for many uses. It is a good dispersant and can be useful for corrosion and rust prevention. But it shouldn’t be used to lubricate moving parts — especially metal on metal.

It’s also a penetrant. But it’s not usually the best penetrant. Ultimately, there are some situations in which you should never use WD-40.

Let’s take a look at where WD40 doesn’t perform as well as other products, and where NOT to use the original formula WD40 under any circumstances.

Drive Chains

Because WD-40 isn’t a great lubricant, it doesn’t work well at all on drive chains of any kind, including motorcycle chains and sprockets. Chain lube should also be specifically designed to avoid attracting dust, which isn’t a feature of WD-40. Here are a couple of better solutions that are perfect for your bicycle chain, too.

Door Locks

While you may be tempted to squirt a little WD-40 into your locks to keep them working well, it won’t do the trick. In fact, it’s also likely to do some harm. WD-40 can cause a gummy buildup, eventually preventing locks from working properly.

The best type of lubrication for this purpose is specifically designed for locks. These dry lubricants repel dust and dirt and keep your lock from building up a gunky and sticky mess. This one contains no oil, grease, graphite, or silicone.

Hinges

Okay, we’ve all done it. Seriously, raise your hand if you’ve ever shot a spray of WD40 into a few door hinges. ✋ Yes, you in the back row, too. ✋

But, the truth is that WD-40 isn’t the best choice for squeaky door hinges. First, it really doesn’t contain sufficient lubrication to oil the hinge effectively for long. Second, although it might temporarily stop a hinge from squeaking, it can also attract dust and dirt, which won’t help the hinge work smoothly in the long run.

WD-40 does make a special silicone version that’s a better choice for smooth and quiet hinge operation. It’s also super clean, so it won’t make a mess of the door jamb.

Bike Chains

Here’s another thing most of us have done at some point… spray a little WD-40 on our bike chain.While it isn’t likely to damage anything, regular WD-40 isn’t the right lube for a bike chain.

Specialist bike shops will surely back us up on this one. You want something that can both lubricate and prevent corrosion and rust. Due to the amount of exposure a bike chain gets from being so close to the ground, it’s especially important for the health of the chain in the longer term that lube doesn’t attract dust.

It should also contain anti-corrosion agents for preventing rust. For best results, use an actual bike chain lube instead.

Garage Doors

Again, the original formula WD-40 isn’t a good lubricant, and a garage door requires an excellent lubricant.

Remember, too, that garage doors often use components made of rubber, plastic, or nylon and all of these parts could be damaged by WD40.

RV Slide-Out Seals

WD-40 can ultimately damage many types of plastic and rubber. It’s also important to repeat — WD-40 can attract dirt, dust, and other debris. This is exactly what you don’t want on your RV slide-out seals.

As we noted in our post How to care for RV slide-out seals, we’ve only talcum/baby powder (talc – not corn starch) on our seals for years. And we’ve still got all of the original seals on our 2005 Newmar Mountain Aire after 18 years of full-timing in it.

We’ve even got a post on maintaining slide out seals under slide toppers. Again, we use only talc-based powder. (Don’t worry – we address concerns about talc in the post.)

While we’re on the topic, if you’ve got issues with your RV slide-outs, or if you just need more information about slide-outs in general, check out our complete guide to the RV slide out.

Trailer Hitch Parts

It’s pretty tempting to grab a handy can of WD40 to lube those trailer hitch connections, but we advise against that. The oil in WD40 is very light but it does leave a slight residue behind. As we’ve mentioned, that can attract dust, dirt, and other debris as you drive down the road. Instead, use good-quality dry lithium grease.

Gears

Along the same lines, WD-40 can attract dust and dirt that sticks to gears, so it shouldn’t be used on gears of any type. Since there are many types of gears, and many types and viscosities of gear oils, we’ll refer you to this article from Machinery Lubrication for additional information.

Plastic or Rubber Components

As mentioned earlier, WD-40 can cause rubber to deteriorate and plastics to crack. This includes clear polystyrene and polycarbonate. For this reason, rubber and plastic components are prime examples of where not to use WD-40.

Electronics

WD40 shouldn’t be used on sensitive electronics because it contains a petroleum-based lubricant that can damage them. It’s better to use a dedicated electronics cleaner like the one below. It uses a petroleum distillate and alcohol that’s safe for surrounding plastics, evaporates very quickly, and leaves no residue behind.

Firearms

WD-40 is not designed to clean firearms and can lead to rust and corrosion. Opt instead for a specialized gun bore cleaner and lubricant:

Musical Instruments

WD-40 should never be used on musical instruments for the same reason it shouldn’t be used on firearms. Using WD-40 on a brass instrument can cause rust and corrosion. The same is true if you try to unstick keys on a woodwind instrument. If you use WD-40 on a musical instrument, you risk destroying it or at least causing costly damage.

For brass instruments, only use a premium valve oil like this one or another oil recommended by the manufacturer of your instrument:

For woodwind instruments, use only a high-quality medium-consistency key oil like this one:

As a Penetrant

We might say that the original WD40 is a jack of all trades but a master of none. While many people use it as a penetrant or lubricant, it really doesn’t shine at either, and can even be harmful.

Need a good penetrant? Try something dedicated to the task:

Computer Keys

Don’t do this! WD-40 can damage plastic and attract dust, crumbs, and everything else to your keyboard while also potentially causing damage to the components under the keys.

Instead, lightly dampen a soft, lint-free cloth with water to wipe down the keys. Then use compressed air to remove dust, crumbs, hair, and other loose debris stuck between the keys. You can finish up by using a disinfecting wipe to gently wipe down the keyboard.

You can also keep a product like this on hand for light-duty cleaning. These are great for the screens of all of your devices.

To Loosen Stuck Nuts & Bolts

Will WD-40 loosen stuck nuts & bolts? It might or might not. As much as we love WD-40 for its many uses, it’s not the best bet for loosening really stuck or rusted-on nuts & bolts.

We prefer to keep some top-tier support on hand for this purpose. We mentioned the penetrants Kroil and PB Blaster above, which can be used for this. But our #1 choice for stuck nuts & bolts has always been Liquid Wrench penetrating oil.

I grew up with a little bottle on my Dad’s workshop bench at all times. A stuck bolt would always lead to Dad reaching for the Liquid Wrench, applying a little, then tapping on the bolt to work it in. Amazing stuff!

As a Treadmill Belt Lubricant

Using the original WD-40 to lubricate a treadmill belt is a good way to destroy the belt over time. Instead, opt for a product specifically designed to lubricate the components of your treadmill, especially the belt.

RV (or Home) Window Tracks

The original WD40 is not a good option for use as a lubricant for your RV or home window tracks. Not only is it not durable enough, but it can also damage window components. However, the manufacturer of WD-40 has another product that works well to lubricate window tracks.

As a Lighter Fluid

This one should go without saying, but since we’ve heard of this being done, we’re putting it on the list. WD40 is flammable.

And no, that doesn’t mean it makes a good lighter fluid. Using WD-40 as a lighter fluid is extremely dangerous. Use lighter fluid as lighter fluid.

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For Anything That Comes Into Contact With Food

WD40 is not food-safe. Don’t spray it on anything that will come into contact with food, such as grill grates. (Did we also mention that WD-40 is flammable?!)

Can You Think of Any Other Places Where Not to Use WD40?

If you’ve heard of other instances of people using WD-40 that could damage components or cause other problems, add your thoughts and experience in the comments section below.

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