Permatex vs Loctite: Threadlockers & Sealants

Permatex vs Loctite: Threadlockers & Sealants
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Which brand is the best for thread lockers and sealants – Permatex or Loctite? Both brands offer a wide range of products that claim to keep bolts, screws, and nuts secure. But how do they stack up against each other?

I’ve seen so many people get confused about these construction adhesives that I finally decided to do a comprehensive post on these two. Choosing between Permatex vs. Loctite can be a close call, as both general-purpose adhesives are promoted for their heavy-duty applications.

Threadlockers and sealants are essential components in the automotive, manufacturing, and repair industries. They prevent loosening and leakage of joints, ensuring the longevity and integrity of the machinery. However, choosing the right product can be a daunting task, especially when so many options are available in the market.

What Is the Difference Between a Threadlocker and a Sealant?

Thread locker and sealant are two distinct adhesive products with different purposes.

Thread locker stops threaded fasteners from loosening due to vibration or external forces. It is applied to screws, nuts, bolts, or other threaded fasteners. The bond created by the thread locker is strong and long-lasting. Different strengths of thread lock alternatives are available, depending on the application.

A sealant is an adhesive that seals two surfaces to prevent fluid or gas leakage. It’s used in plumbing, automotive engines, and construction. It can be applied to metal, plastic, and rubber surfaces. It comes in liquid, paste, or tape form for different sealing applications in low or high-pressure environments.

Deciding on the best thread locker or sealant can be tough. In this article, we’ll compare Permatex and Loctite, two popular brands. We’ll look at their features, strengths, and weaknesses to help you make a well-informed decision. Let’s get started.

Permatex and Loctite Types of Adhesive

Today we’ll be looking at both brands’ threadlockers and thread sealants. Common identical products here are:

  • Loctite 565 vs. Permatex 56521 for thread sealants
  • Loctite 242 vs. Permatex 24200 for threadlockers (medium strength)
  • Loctite 515 (or 518) vs. Permatex 5183 for anaerobic thread-locking adhesives

Do you notice it from the get-go? The numbers are designed for cross-referencing, and the color codes are used for comparison, often mentioned in the name rather than the packaging.

Let’s take a look at the differences between them – if any at all in some cases 🙂

02/18/2024 04:28 am GMT Lasso Brag
A little trivia: Loctite bought Permatex in 1972, and around 2000, they sold them back. Currently, Permatex’s owner is Illinois Tool Works – the same company that owns Hobart and Miller welders, Tapcon fasteners, and many more.

Loctite vs. Permatex: Threadlockers

The threadlocker products from both brands are almost the same. By ‘almost,’ I mean you won’t notice any significant difference with general use. Both are blue threadlockers that prevent screws, nuts, and bolts from loosening due to vibration or other factors.

There are, however, two small details.

#1 Gel Blue Thread Locker

Permatex has gel twist-type thread lockers like the 24010 that are ideal for use in high-vibration environments. The gel formula ensures that the threadlocker stays where it is applied, preventing drips and messes.


The product is identical to both brands’ 242 products. However, it introduces two improvements:

  • It works with bigger screws: 1/4″ to 1″.

  • Its advantageous gel-based structure makes it easier to apply (especially on vertical applications).

#2 Difference in Fixture Time

Permatex is a bit slower in terms of a fixture time, taking around 20 minutes to set, compared to Loctite 242, which sets in 15 minutes. Both fully cure after 24 hours. Permatex is also known for its higher viscosity, making it better suited for larger gaps and rougher surfaces. Loctite 242, on the other hand, is known for its versatility and ability to work with a wider range of materials.

Note: If you want a medium-strength threadlocker and don’t care about gels, check out Loctite 243. It’s an improved version of 242 and 24200 – it can be applied to a surface without surface preparation and is oil resistant.

Keeps fasteners even tighter and doesn’t require you to thoroughly clean the threads beforehand.

Our Pick
Loctite 243
  • Best thread locker for general use.
  • Better oil tolerance for easier application
  • Oil resistant, holds very tight, and doesn’t require heat if you decide to remove it.
  • Great longevity.
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Same Color Scheme and Threadlocker Hold

So, is Permatex threadlocker as good as Loctite? Permatex and Loctite threadlockers have similar characteristics. They even share the same color scheme for the strength/hold of their threadlockers:

  • Purple for low strength

  • Blue for medium strength

  • Red for high (permanent) strength

The blue threadlockers will be OK for 90% of your projects. If you need more info on Loctite’s products, I’ve compared their threadlockers already. The most important thing is that this little adhesive should be among your regular hand tools, as you will use it plenty of times. It will make the most challenging projects, like ensuring eyeglass screws, ten times easier. 

You can check the Permatex 24200 and read what people say about it. Still, as I said, I recommend Loctite 243 over any other medium-strength locker product.

Thread Sealants: Permatex 565221 vs. Loctite 565

Two favorites of plumbers and mechanics – but not just them. You’d need these two for a variety of pipe/fitting sealing jobs, from waste management to hydraulic lines, brake fittings, air conditioners…

I’ll be frank: they’re literally the same thing.

Both thread locker products work with any NPT (National Pipe Thread) that’s up to 2″ – that’s 5cm for those using the metric system.

Also, both withstand the pressure of up to 10,000 psi.

Surprise, surprise – both of them also have a temperature range of -65°F to 300°F.

I mean, if you have any specific brand preference, go ahead and buy whichever you feel better about. Even the tubes have the same design.

The important thing is that you won’t have any leakages. And will also benefit that nut-and-bolt applications won’t suffer rusting/corroding after you use either.

$14.01 ($8.29 / Fl Oz)
02/18/2024 04:28 am GMT Lasso Brag

Loctite 518 vs. Permatex 5183 gasket makers: Small differences

OK, this time, a little more variety deserves mentioning. I had to dig in Henkel’s official site to find it, and this is the bread for a multi-billion dollar company. 

A small difference between this Loctite and the 5183 counterparts is the gap support:

Loctite 518 fills gaps up to 0.25mm (0.01″), while Permatex 5183 goes wider with gap support of up to 0.38mm (0.015″).

Both of these are anaerobic gasket makers/flange sealants. You want to use them with metal parts and machinery. Aluminum, iron, steel – anytime you need a quick repair you can use either of these.

Probably you’ve noticed that Loctite 518 is very hard to find – both in physical stores and online…

A more accessible substitute is Loctite 515. It works the same for most situations, with two caveats.

First, it’s subpar for aluminum flanges. Second, it sets faster, so its cure time might be faster than the other two with more active metals like brass.

Permatex 51813
  • Fills bigger gaps which can be important in some cases.
  • Otherwise has the same function and properties as Loctite 515/518.
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02/18/2024 04:54 am GMT

Closing words: Cross-reference table & definitions

Finally, is Permatex the same as Loctite? won’t lie – much as I like using both brands’ products, all the classification going on can turn anyone’s head spinning. Why would I be writing this article otherwise, right?

If you want a somewhat complete Permatex vs. Loctite cross-reference table, one already exists. You can check it on Permatex’s official site.

Some people don’t make a difference between threadlockers and thread sealants. As I’ve compared Loctite and Permatex in both of these uses, let’s bring up some short definitions.

Threadlockers: These are adhesives you apply on bolts/fasteners/screws, so they stay tight. In addition, both brands’ threadlockers have a formula that includes protection from corrosion.

Thread sealants: Here, you seal two connectors. As I mentioned, these are generally pipes – from water pump bolts to air conditioning or projects dealing with anything automotive.

With gasket makers, I recommend you refer to Permatex’s guide on what mistakes not to make when using them. From time to time, we all face the toughest projects, and failure comes harder than anything else.

Are you interested in learning more about this service technology and want to know more about the sustainable tech of standard glue or epoxies? I’ve written a Loctite vs Gorilla Glue comparison – check it out 🙂


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