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Loctite 243 Or 242

Loctite 243 Or 242: Which Should You Choose?

Loctite threadlockers are widely used for sealing and securing bolts in vehicle repairs. But it comes in different types. So which should you choose between Loctite 243 vs. 242?

While they may seem similar, some key differences can make one a better choice than the other for your specific needs. 

If you’re ready to make a purchase but not sure whether to buy Loctite 243 or 242, let our comparison help you! We’ve done some research, so you don’t have to. 

loctite 243 or 242

Loctite 243 Or 242: Comparison Table

Technically, Loctite 243 is the upgraded version of 242. Hence, in some cases, the newer product outweighs its previous version in some terms, such as oil tolerance and no need for the primer layer. 

However, because they belong to the same category of Loctite Blue, you will notice more similarities between them. This comparison chart will help you picture how these adhesives are different and similar.  

Criteria  Loctite 242 Loctite 243
Thread Size  ¼ inch – ¾ inch ¼ inch – ¾ inch
Strength  Medium  Medium 
Breakaway Torque  11.5 Nm 26 Nm
Curing Time  24 hours 24 hours 
Oil Tolerance No Yes 
Temperature Range -65 to 300°F  -65 to 300°F 
Primer Requirement Yes No 
Maintenance Necessary   Not necessary  
Uses  Sealing and securing metal bolts and nuts Ceiling threaded fasteners 
Removal  Easy Easy 


What Is The Difference Between Loctite 243 Vs. 242?

You can use Loctite threadlocker on any threaded fasteners in your car that are prone to physical impact or vibration. For example, you can use it for suspension components or engine mounts if your car jerks when slowing down

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Loctite offers different types of threadlockers based on their strength. For example:

  • Low strength: 221 and 222 (Loctite Purple)
  • Medium strength: 242 and 243 (Loctite Blue)
  • High strength: 262, 272, and 271 (Loctite Red)

Loctite 242 and 243 threadlockers have medium strength, which is one of their similarities. Here are other features of of Blue Loctite 242 vs. 243

Thread Size

You can use both of these adhesive types for ¼-inch to ¾-inch threads. It applies to various applications, such as in automotive, domestic uses, and light maintenance.  

Breakaway Torque

The breakaway torque is the amount of force required to bust a nut or screw loose after the adhesive has fully cured. 

Although Loctite 243 and 242 are medium-strength threadlockers, they have different breakaway torque. The torque on Loctite 243 is 26 Nm (Newton-meter), while it’s only 11.5 for Loctite 242. 

Curing Time 

These threadlockers need about ten minutes to dry and 24 hours to fully cure on steel. If you work with less-active materials, the curing time will be longer. 

When cured, the adhesives become non-flammable and solvent-resistant solids. They can also wick away moisture. 

Oil Tolerance

Oil tolerance is one of the most significant differences between Loctite 242 vs. 243. The 243 is the clear winner in this round. 

It may take some oil contamination, but its mechanical qualities don’t change. Hence, you can easily apply the adhesive on surfaces that often struggle with oil. 

Temperature Range

Loctite 243 temperature range is from -65 to 300°F . As a result, you can heat a hard bolt around 250°F to loosen it if needed. And to extend the adhesive’s lifespan, consider freezing it. 

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Primer Requirement

Before applying the adhesive, you often have to give the surface a primer layer so the adhesive can stick to it easier. However, if you use Loctite 243, you can skip this step because it’s oil-resistant. 


The oil tolerance feature is a big plus of Loctite 243. You don’t need to clean the surface before applying and won’t worry about oil accumulation. 


These two threadlockers have the same strength and temperature range. However, we often use them for different purposes. 

For example, Loctite 243 is better at sealing and securing nuts and bolts. Mechanics like to use this adhesive to reduce vibration and shock in the system. 

On the other hand, Loctite 242 is more prevalent in ceiling threaded fasteners. It offers sufficient strength for the connections.  


Because Loctite Blue has a medium strength, you can easily remove it using simple tools. Here is how to do it:

  • Wipe the adhesive within five minutes after application. 
  • Remove the dried section with a putty knife. 
  • Soak the nuts in methylene chloride. 
  • Get rid of the remaining using a metal brush.  

Which Should You Choose, Loctite 243 or 242?

Loctite 242 and 243 are both medium-strength threadlockers. They have many things in common, with a few differences. So, your choice between Loctite 243 vs. 242 depends on your specific needs. 

Loctite 242 is more common to use on fasteners that you need to disassemble in the future. This feature makes it an excellent idea for applications where vibration may lead to loosening the fasteners and you want to remove them with hand tools. 

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You can consider applying Loctite 242 in nuts, screws, and bolts in vehicle repairs. It’s suitable for engine mounts, too. 

On the other hand, Loctite 243 is more popular for pre-assembled fasteners. It forms a solid attachment that you can’t remove easily in the future. 

Besides, if you are looking for a threadlocker in oily areas, the oil tolerance of Loctite 243 will make it shine.  

Other Loctite Threadlocker Series

The medium-strength Loctite threadlocker is the most common choice. But you still have two other options:

Low-Strength Threadlocker

This Purple line is ideal for general use as it allows you to move quickly after application. 

You can choose Loctite 222 or 221 and use them interchangeably. They work well for low-torque items, such as scope mounting. 

The difference between them is the breakaway torque. The torque on 22 is 8.5 Nm, while this figure for the 22 is 6 Nm. 

High-Strength Threadlocker

Loctite 271, 272, and 262 are heavy-duty adhesives, with 272 being the strongest. If you need a threadlocker that can withstand high heat, go for this series. 

If you want to remove the adhesive, you must use sweat, heat, and hand tools. Hence, they are perfect options for heavy-duty automotive applications. 


There are many similarities and differences between Loctite 243 vs. 242. You can decide on the best based on your specific needs. 

If you know someone who is considering Loctite 243 or 242, share this blog post with them! It may help them make an informed decision. 

Thank you for reading and sharing! 


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