Why Do Locksmiths Hate WD-40 (Here’s The Truth)

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Many people who encounter a sticky lock, or even any other mechanical device that needs lubrication, reach for the WD40 can as an automatic response.

Even though the WD40 may provide a temporary fix for your sticky lock, it is not the best solution for this problem.

Why do locksmiths hate WD40, and what would be the better lubricant to use on your locks?

Locksmiths hate WD40 because it is not a lubricant; it is a solvent. The solvent dissolves any lubricant in the lock mechanism, and when the solvent dries, it leaves a sticky residue, which dust and grime stick to. Over time, this makes a sticky lock even worse and even more difficult to fix.

WD40 can be found in most households as a common item, but it is often misused in the wrong application.

A lock is a relatively delicate piece of technology that is machined to close tolerances, which means that it does not take much to cause the lock to stick.

In most cases, people think WD40 is the right product to use on a sticky lock because it initially seems to do the job and loosen the lock mechanism up.

WD40 used on a lock may be a short-term fix, but it has long-term consequences!

Why Is WD40 Bad For Locks?

WD40 is by no means a bad product, but when used inappropriately, it can cause issues that compound the very problem it was used to alleviate! The main reason that WD40 is used inappropriately is that it initially seems to perform wonderfully in loosening up stuck or sticky mechanisms.

WD40 is a water-displacing spray and a solvent, which may not seem like a bad thing to put in your lock at first thought.

Displacing moisture and water may seem like a good concept because it will keep the metal mechanism in the lock from rusting and becoming difficult to operate.

The water-displacing component of WD40 is not necessarily the main problem; it is the other active ingredients in the product that dissolve oils and grease that is the problem.

Grease and oils can become hard over time, limiting the movement of parts in the lock mechanism. What WD40 does is dissolve the old grease and oils, which is why it initially makes the lock work better!

However, because it is a solvent, the WD40 removes all the oils and grease in the mechanism of the lock. This results in two problems for the lock mechanism after the application of WD40.

  • All the oil is removed from the inside of the lock, which leaves the mechanism dry and free of oil, which can cause the lock to stick.
  • As the WD40 dries, the dissolved oils dry out and leave a sticky residue on the parts, which causes dust and dirt to stick to the surfaces of the lock mechanism. This makes the lock even stickier than it was before.

The intention for WD40 is for the product to be used to displace moisture, loosen up stuck components but not left on the parts as a replacement for a lubricant. After the WD40 has been applied, the parts should be wiped down, and a proper lubricant applied to the mechanism.

It is not possible to wipe down the inside of a lock, which is why locksmiths hate WD40 being used on locks. It would be a better choice to not use WD40 at all and rather use a different lubricant altogether on your locks.

Does WD40 Make Sticking Locks Worse And Harder To Repair?

WD40 does work initially when used on the lock, but in some cases, after some time, the stickiness of the lock will return. This is a result of the accumulation of dust and dirt that has stuck to the residue inside the lock.

When a locksmith is called out to fix a lock in this condition, it is often difficult to even pick the lock to get it open. This is because the pins are stuck and jammed up from the dust and dirt in the lock. Some locks can only be removed once they have been opened. It makes life difficult for the locksmith if the lock mechanism is stuck.

If the client does not want the lock replaced but rather repaired, the locksmith will need to strip the lock completely to clean off the build-up of grime on the component parts before lubricating them correctly and re-assembling the lock.

This takes additional time to do and makes it harder for the locksmith to accomplish, which in turn increases the cost for the client.

When Do Locksmiths Use WD40?

Locksmiths dislike WD40 being used as a lubricant, but that is not to say that locksmiths do not use WD40 at all.

There is a place for the product, and this is usually when a client needs a stuck lock replaced. The lock will need to be opened before it can be removed.

WD40 does a great job in this role to loosen up the mechanism so that the locksmith can pick the lock open in preparation for removal and replacement.

What Is The Best Lubricant For Locks?

If WD40 is not an ideal lubricant to use on your locks, what should you be using instead? Should you use oil instead for locks?

In times gone by, a few drops of 3-In-1 machine oil was used to lubricate locks, but this is a rather viscous oil, which does not penetrate deeply. The viscosity can also attract dust and dirt to stick to the oil rather than flushing the dirt out.

There are a number of products that are preferable to using either WD-40 or a viscous oil product.

  • Graphite. Graphite is regularly used as a lubricant for locks because it is a dry product that does not accumulate dust and dirt. However, in humid conditions, the moisture content from the air can be absorbed by the graphite, turning it into a gummy paste, which causes locks to become stuck. In dry climates, graphite works well as a lubricant.
  • PTFE or Teflon. PTFE is another “dry” lubricant that is a better choice than graphite in humid conditions. There are several PTFE lock lubricant products available, such as Master Lock.
  • Chain lube. Chain lube is a popular lubricator for locks because it is a low viscosity lubricant that penetrates deeply into the mechanism. The low viscosity serves to flush out any dirt and dust, and it leaves behind a thin film of lubricant. A product in this category that is frequently used is Tri-Flow.

Chain lubricants for motorcycles and bicycles are a frequent choice by locksmiths because the lubrication in the product is a high-quality lubricant of low viscosity, and it is less sticky than high viscosity oils.

The chain oil is designed to penetrate deeply between the links of a chain and to keep the chain lubricated in high-temperature conditions. These qualities make it a great alternative lubricant for locks!


WD40 does have lubricating properties, but it is not long-lasting and is not the most ideal lubricant for locks. The properties of WD40 actually dissolve whatever lubrication was inside the lock, and the residue that is left behind becomes an attractant to dust and dirt.

A low viscosity, high penetrating oil is the best lubricant to use on your locks.

Good oils for this purpose are the aerosol pressurized chain lubricants that are made for motorcycle and bicycle drive chains. These lubricants penetrate deep into the lock mechanism and reduce the accumulation of dirt in the mechanism while promoting the smooth operation of the moving parts.

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