Loctite 243 Vs 222: Which One Is Better?

As someone who spends half their weekend working on cars, motorcycles, and finicky gadgets, I’ve learned that a project is only as good as the fasteners holding it together. And when it comes to fasteners, the name Loctite is king.

But walking into the store and seeing a wall of red, blue, purple, and green bottles is confusing. I’m here to clear up the most common battle: Loctite 243 (blue) versus Loctite 222 (purple). I’ll break down which one you should be reaching for, because using the wrong one is, at best, an annoyance, and at worst, a disaster.

A Brief Comparison Table

My Experience With Loctite 222

My first real “aha!” moment with Loctite 222 wasn’t on a car; it was on a high-end remote-control truck.

If you’ve ever been in that hobby, you know it’s a world of tiny, high-vibration metal parts.

I was constantly losing microscopic set screws that held the drivetrain together.

I tried a tiny dab of the “classic” blue threadlocker (an older 242, at the time), and when I needed to do maintenance, I promptly stripped the hex head on a $20 part, turning it into a $50 problem.

I was furious.

Then, a veteran at the RC track showed me his little purple bottle of Loctite 222. He called it “the modeler’s friend.” I put a tiny, tiny drop on the threads of my new set screw, and it felt… wrong. It didn’t have that aggressive “grab.” But the next race day, nothing came loose. And more importantly, the next maintenance day, I put my hex driver in, gave it a gentle twist, and it broke free with a satisfying, clean click. No stripping, no heat, no panic.

Since then, Loctite 222 has become my go-to for anything delicate. I use it in my computer-building hobby for the tiny M3 screws that hold down water-cooling components. I’ve used it on the adjustment screws for a rifle scope, where I need it to stay put from the shock of recoil but still be adjustable later.

I’ve even used it on the notoriously loose screws on my sunglasses. It’s not a “locker” in the way you think of 243 or 271; it’s a “vibration damper.” It just adds enough friction to stop a fastener from backing out on its own, without ever making you fight it. It’s the definition of a low-stakes, high-reward product.

Pros Of Loctite 222

• The Gift Of Removability: This is its entire reason for existing. The low-strength formula, identified by its purple color, is designed to be disassembled with the same tool you used to install it.¹ There is no need for cheater bars, impact wrenches, or the dreaded propane torch. For any fastener under 1/4-inch (M6), this is a godsend. On small set screws, carburetor adjustment screws, or electronics, using a stronger threadlocker is a one-way ticket to stripping the head or shearing the bolt. Loctite 222 holds against vibration but surrenders gracefully when you need it to.² This “serviceability” is its number one pro, and it’s a big one.
• Protects Delicate Fasteners And Materials: I work a lot with aluminum and brass, especially on motorcycle and small-engine parts. These soft metals cannot handle the stress of a medium-strength (blue) or high-strength (red) threadlocker. When you go to remove a bolt secured with blue Loctite from an aluminum housing, you have a very real chance of pulling the threads right out of the housing, turning a 10-minute job into a weekend of drilling, tapping, and installing Heli-Coils. Loctite 222 is gentle. Its breakaway torque is low enough that it will always be the weakest link, ensuring the fastener comes out clean without damaging the expensive, delicate, or irreplaceable parts it’s threaded into.
• Ideal For Adjustment-Critical Applications: Think about things that you must be able to fine-tune. I use it for the calibration screws on machinery, the leveling feet on a workbench, or the tiny screws on a rifle scope’s windage and elevation turrets. These are parts that need to be set, locked against vibration, and then potentially re-adjusted later. Loctite 222 provides just enough anaerobic curing to “set” the fastener in place, preventing it from creeping under vibration, but it doesn’t create a permanent bond.³ This allows for precision and serviceability in one package.
• Good Lubricity During Assembly: One thing people don’t often realize about threadlockers is that they act as a lubricant before they cure. This is especially important for small, fine-pitch screws. The liquid helps prevent galling or cross-threading during assembly. This means you are more likely to achieve a correct and consistent clamping force (torque) on your delicate fasteners. With 222, you get a smooth assembly, a secure “hold,” and an easy disassembly, which is the perfect trifecta for any work involving small-scale, precision mechanics. It’s the product you use when you want to be “safe, not sorry.”

Cons Of Loctite 222

• Extremely Limited Strength: This is the other side of its primary “pro.” This stuff is low strength. Do not mistake it for a structural adhesive. If you use Loctite 222 on a bolt that is 1/2-inch, holding a vibrating engine mount, it will fail. It simply does not have the shear strength to resist high-torque loads or extreme, violent vibration. This is the most common user error—people see “Loctite” and assume it will lock anything. This is not a general-purpose threadlocker. It’s a specialty product for a specific low-strength, small-fastener application. If your bolt is bigger than your pinky finger (M6 / 1/4″), 222 is almost certainly the wrong choice.
• Requires A Meticulously Clean Surface: Unlike its more modern 243 counterpart, Loctite 222 does not have “oil tolerant” chemistry. It is an older formula that requires a surgically clean surface to cure properly. The anaerobic curing process (curing in the absence of air and presence of metal ions) is easily inhibited by any oil, grease, or grime. You must use a good degreaser (like Loctite’s own ODC-free cleaner or even simple brake cleaner) and a clean rag to perfectly clean both the male (bolt) and female (hole) threads.⁴ If you fail to do this, the 222 may never cure at all, giving you a false sense of security while the bolt is vibrating loose inside.
• Slower Cure Time On Passive Metals: This anaerobic curing process relies on metal ions to “kick off” the reaction. “Active” metals like brass, copper, and mild steel have plenty of ions and will cure 222 relatively quickly (e.g., 20-30 minute fixture time). But “passive” substrates like stainless steel, aluminum, black oxide coatings, and plated fasteners have very few free ions. On these materials, Loctite 222 can take ages to cure—sometimes 24 hours or more to reach full strength. This can be a major problem in a fast-paced environment. While you can use a Loctite primer/activator (like SF 7649) to speed this up, that’s an extra step and an extra expense.⁵
• Lower Temperature Resistance: While this isn’t a problem for most applications, it’s a limiting factor. Loctite 222 is rated for service up to 150°C (302°F).⁶ This is more than enough for electronics, hobby parts, and most ambient-temperature machinery. However, on anything that gets even moderately hot, like parts near an engine’s exhaust manifold, near a brake assembly, or inside certain industrial equipment, 150°C can be reached, at which point the 222 will soften and lose all its locking ability. This makes it a non-starter for many automotive or engine-related applications where the more robust 243 would be the minimum requirement.

Maintenance Tips For Loctite 222

• Preparation Is 90% Of The Battle: This is the most critical rule for 222. Because this formula is not oil-tolerant, you live and die by your prep work. You must, without exception, degrease the fasteners. I use Loctite SF 7063/7064, which is a non-CFC cleaner designed for this exact purpose.⁷ In a pinch, high-quality automotive brake cleaner (the kind that leaves zero residue) on a clean, lint-free shop towel will also work. You must clean both the bolt threads and the internal threads of the hole. If you apply 222 to an oily “as-received” fastener, you are just wasting your time and threadlocker; it will not cure properly.
• Use An Activator For Passive Metals: If you are working with stainless steel, titanium, plated zinc, or black oxide fasteners, 222 will take a very, very long time to cure on its own—if it ever reaches full strength at all.⁸ These are “inactive” or “passive” substrates. To get a reliable cure, you need a primer/activator, like Loctite SF 7649.⁹ You spray a light coat on one or both surfaces. This chemical primer “activates” the surface and kicks off the anaerobic curing process, ensuring a fast and complete bond. Be warned: this can make the fixture time very fast (sometimes under a minute), so have your parts ready to assemble.
• Understand Anaerobic Curing: I often see people put a drop of Loctite on a bolt, set it on the workbench, and then wonder why it’s “still wet” an hour later. Loctite threadlockers are anaerobic.¹⁰ This means they cure only in the absence of air (i.e., inside the threads) and the presence of metal.¹¹ That drop on your workbench is exposed to air, so it will never cure. This is also why the bottles are only half-full. That air in the bottle is what keeps the liquid stable. So, apply the drop (a little goes a long way) to the bolt threads, and then immediately assemble the parts. The curing process only begins once you’ve tightened the fastener.
• Storage And Shelf Life: You must store your Loctite 222 properly. The ideal environment is in its original bottle, in a cool, dark, dry place. Heat is the enemy of all adhesives, and it will shorten the shelf life. The official shelf life for an unopened bottle is typically 24 months, but I’ve had bottles last much longer when stored correctly. The key is to keep it away from extreme temperatures (like a hot garage in the summer). Also, that “half-full” bottle is by design. Do not transfer it to a smaller, “full” container, as this will remove the air, and the entire bottle will cure into a solid, purple, and very expensive brick.
• Removal And Re-Application: The beauty of 222 is the removal. You just take your standard hand tool (screwdriver, hex key) and turn it. You should feel a small “pop” or “click” as the bond breaks. That’s it. Once the bolt is out, you’ll see a white-ish, chalky purple residue. This is the cured anaerobic plastic.¹² Before you re-apply Loctite 222 for reassembly, you should ideally clean this old residue out. A brass brush or a thread pick works well. This ensures the new application has a clean surface to bond to, giving you a fresh, reliable lock.

Read more: My Thoughts on CCIYU Auto Parts

My Experience With Loctite 243

If Loctite 222 is my “specialty” product, Loctite 243 is my “workhorse.”

This is the blue bottle that lives in the top drawer of my main toolbox.

My trust in 243 was forged in the heat and vibration of my old V-twin motorcycle.

That bike was a paint-shaker on wheels, and it would vibrate everything loose: fender bolts, mirror stalks, license plate brackets.

My first “fix” was to just crank down on the bolts, which only led to stripped threads and broken bolts.

Then I learned about Loctite 243. The “243” is the modern, upgraded version of the “242” everyone’s dad used.¹³ The key difference, and the reason I love it, is that 243 is oil tolerant and primerless.¹⁴ I was working on the bolts for my gearbox cover, a place that is always a little oily, no matter how much I clean it. I gave them a good wipe, but I knew they weren’t “surgically” clean. I applied a drop of 243 to each bolt and torqued them to spec.

The peace of mind was immediate. I no longer had to stop every 50 miles to tighten my mirrors. The bolts on my lawnmower’s vibrating engine shroud stayed put all season. The caliper-to-knuckle bolts on my car, which are critical safety components, get a drop of 243 every time I do a brake job.

The removal is just as I’d want it: it’s not “easy” like 222, but it’s not “hard” like red 271. You put a wrench on it, you give it a good, solid pull (no wimpy-wristing it), and it breaks free with a pop. It gives you enough resistance to know it was working, but it never makes you feel like you’re about to shear the bolt. It’s the perfect, all-purpose, “trust me, this will stay put but you can still get it off” solution.

Pros Of Loctite 243

• The Perfect “Serviceable” Strength: Loctite 243 is the goldilocks of threadlockers. It’s not too weak, and it’s not too strong. The “medium” strength is robust enough to hold critical fasteners in place against heavy shock, heat cycling, and vibration.¹⁵ Think of pump motors, gearbox flanges, engine mounts, or automotive suspension components. It will prevent these bolts from backing out. However, it’s not so strong that it’s permanent. It is specifically designed to be “removable with standard hand tools.”¹⁶ It may require a long-handled ratchet or a breaker bar for a large bolt, but it will come apart without you having to bust out a 2000°F torch, which is the case for red, high-strength threadlockers.
• Superior Oil Tolerance: This is the single biggest advantage of 243 over its predecessor, 242, and over many competitors.¹⁷ 243 is formulated to cure right through minor contaminations of industrial oils, cutting fluids, and corrosion-prevention greases.¹⁸ In a real-world shop, it’s almost impossible to get threads (especially internal female threads in an engine block) 100% free of oil. With 243, you don’t have to. You just wipe the bolt down and apply the drop. This “as-received” fastener capability saves an enormous amount of time and, more importantly, provides a reliable cure where other threadlockers would fail. This makes it far more “user-friendly” and robust for non-laboratory conditions.
• Primerless Curing On Passive Metals: This is the other massive upgrade.¹⁹ Just like 222, older formulas (like 242) struggled to cure on inactive substrates like stainless steel, plated bolts, or aluminum. They required a separate, expensive, and time-consuming primer/activator step. Loctite 243 is “primerless,” meaning it has an enhanced chemical formula that will reliably cure on its own, even on stainless steel.²⁰ This makes it truly a “one-bottle” solution for 90% of the fasteners you’ll encounter in a modern machine, which uses a huge mix of metals. This versatility is its greatest strength.
• Higher Temperature Resistance: Loctite 243 has a higher service temperature range than 222, rated up to 180°C (360°F).²¹ This is a significant upgrade and makes it suitable for a much wider range of automotive and industrial applications. This 180°C limit means it’s perfectly safe for use on parts like valve covers, water pumps, oil pan bolts, and intake manifold fasteners—all areas that get hot during operation but stay well below this threshold. This heat resistance ensures the threadlocker maintains its strength and doesn’t soften or fail when the engine or machine gets up to operating temperature.

Cons Of Loctite 243

• Too Strong For Small Or Delicate Fasteners: This is the most common misapplication of blue threadlocker. I’ve seen people strip countless hex screws and snap off M3, M4, and M5 bolts because they used 243 when they should have used 222. The 26 Nm breakaway torque is far too high for a small-diameter fastener. The fastener itself will snap, or you’ll strip the head, long before the Loctite bond breaks. If the bolt is small enough to be in a laptop, on a carburetor, or holding a piece of plastic trim, 243 is the wrong choice. It’s a tool for metal-on-metal, M6-and-up applications.
• It Is Not “Red” Loctite (It’s Not Permanent): On the other end of the spectrum, some users misunderstand 243 and expect it to be a permanent “weld” for a fastener. It is not. It is designed to be removable. If you have a critical, structural fastener that must never come loose (like an engine’s main bearing cap bolt, a flywheel bolt, or a permanent press-fit stud), 243 is not the right choice. For those “never-ever-disassemble” applications, you need a high-strength (Red) threadlocker like Loctite 271, which requires extreme heat (over 250°C) to break.²² Using 243 in a high-strength application can lead to a false sense of security and potential failure.
• Can Be Difficult To Remove If Over-Applied: A little Loctite 243 goes a very long way. A single drop on the leading threads is usually all that’s needed. I’ve had to fight bolts where a previous mechanic “helpfully” slathered the entire bolt in blue threadlocker. This does not make it “more” locked; it just makes it a nightmare to remove. The excess Loctite squeezes out and cures in the gaps, effectively gluing the entire shaft of the bolt, and sometimes even the bolt head, to the part. This multiplies the force needed for removal and can make you think you need heat, even when you shouldn’t.
• Requires Significant Force To Disassemble: While it’s listed as “removable with hand tools,” this can be misleading for a novice. It doesn’t mean it’s “easy” to remove. It means it’s possible with a hand tool. You will need a good-quality wrench or socket, and you will need to apply a firm, steady, and significant amount of force to “break” the bond. It’s not uncommon for a bolt to feel tighter coming out than it did going in. For someone not expecting this, it can feel like the bolt is cross-threaded or seized, which can be an intimidating and nerve-wracking experience.

Maintenance Tips For Loctite 243

• Wipe, Don’t Bathe: The “oil tolerant” feature of 243 is a game-changer, but it’s not magic. It’s designed to tolerate minor contamination, like the light, oily film left over after a quick wipe-down.²³ It is not designed to cure if the bolt is literally dripping with motor oil or caked in heavy-duty grease. The best practice is to always give the fastener a good wipe with a clean shop towel. This removes the excess, giving the 243 the best possible chance to bond directly to the metal, which will always give you the most reliable hold. You’ve traded a 10-minute surgical cleaning (for 242) for a 10-second wipe-down (for 243). Use those 10 seconds.
• Apply The Drop In The Right Place: For a “through-hole” (where the bolt goes all the way through a part and a nut is put on the other side), you should apply a few drops of 243 to the bolt threads in the area where the nut will sit before you put the nut on. For a “blind hole” (where you’re threading the bolt into a part, like an engine block), you should apply the drop to the bolt threads that will be engaged inside the hole. Some people say to put the drop in the hole, but I find this is less precise. It can cause hydraulic lock if you use too much, and it’s harder to ensure full thread engagement. A single drop on the first few male threads is all you need. As you tighten it, the liquid will spread evenly.
• Give It Time To Cure: While Loctite 243 is “primerless,” it still needs time to work, especially on passive metals like stainless steel. The “fixture time” on steel is about 10 minutes, which means it’s “set” and won’t be liquid.²⁴ But it is not at full strength. Full cure strength is typically achieved in 24 hours.²⁵ This is important. If you apply 243 to your motorcycle’s mirror and immediately go for a 100-mile ride on the highway, it may not have had time to cure, and the vibration might still loosen it. A good rule of thumb is to let it sit for at least an hour before applying moderate stress, and 24 hours before you really trust it with its life.
• Removal Technique Is Key: When it’s time to take it apart, you need to use the right technique. Don’t use a short, stubby wrench and “jerk” at it. That’s how you snap bolt heads. Use a long-handled ratchet or breaker bar that allows you to apply slow, steady, and increasing torque. You will feel the tension build, and then pop—the bond will break. This is the anaerobic polymer fracturing. Once it’s broken, it’s broken; the rest of the removal will feel “stiff” but should be smooth. If it’s really stuck (e.g., it was over-applied or on a large-diameter fastener), a little heat from a propane torch (just enough to warm the area) will soften the 243 and make it release much easier.
• Clean The Threads Before Re-Application: Just like with 222, when you remove a bolt that had 243 on it, you’ll see a chalky blue residue. This is the cured adhesive. Before you re-assemble that joint, you need to clean that gunk off. A wire brush (brass for soft metals, steel for steel bolts) or a thread-chasing tap is ideal. If you just apply new 243 on top of the old, caked-on 243, you’ll get a-l) a “gummy” and unreliable new bond and b) an incorrect torque reading, as you’ll be fighting the friction of the old gunk, not achieving the correct bolt stretch (clamp load).

Read more: Comparison Of Leatherman Free T2 And Victorinox

Comparison With Other Brands

• vs. Loctite 242 (The Predecessor): Loctite 243 is the direct, modern replacement for the classic Loctite 242. If you see 242 on the shelf, it’s likely old stock. 242 was the original medium-strength blue, but it had two major weaknesses: it required a spotlessly clean, oil-free surface, and it required a primer/activator to cure on passive metals like stainless steel. 243 solves both of these problems, being both oil-tolerant and primerless.²⁶ There is, in my opinion, no reason to ever buy 242 today if 243 is available. 243 is simply a superior, more robust, and more user-friendly chemical.
• vs. Loctite 271/277 (Red High Strength): This is a common point of confusion. Blue (243) is medium strength; Red (271) is high strength.²⁷ The difference is removability. Blue is designed to come apart with hand tools.²⁸ Red is designed to be permanent.²⁹ You should only use Red Loctite on fasteners you never, ever plan to disassemble through normal maintenance, such as internal engine components, studs set into a block, or press-fit bearings. The only way to reliably remove a Red Loctite-d bolt is with extreme heat (250°C+ / 500°F+) from a torch to literally burn the adhesive and break it down. Using 271 on a simple fender bolt is a catastrophic error.
• vs. Loctite 290 (Green Wicking Grade): Green Loctite is not like the others. 222, 243, and 271 are all “thixotropic”—they are gel-like and are applied before assembly. Loctite 290 (Green) is a wicking-grade, medium-strength liquid.³⁰ It’s as thin as water. Its special purpose is for post-assembly locking. You assemble your parts, tighten the bolts, and then touch the tip of the 290 bottle to the seam where the bolt head and part meet. The liquid’s low viscosity will “wick” down into the assembled threads via capillary action and then cure. It’s a fantastic product for locking pre-assembled fasteners or electrical connectors that you don’t want to disassemble.
• vs. Permatex (The Main Competitor): Permatex is Loctite’s biggest and most direct competitor, and they make excellent, reliable products. You will find their own color-coded equivalents: Permatex Surface Insensitive Threadlocker Blue (24200/24300) is their direct 243 competitor, and Permatex Low Strength Threadlocker Purple (22200) is their 222 competitor. In my experience, they work almost identically. I’ve used both brands interchangeably with great success. For a hobbyist, the choice often comes down to price and availability. Loctite is the “Kleenex” or “Band-Aid” of the industry—the brand name everyone knows—but Permatex is a fantastic, and often slightly cheaper, alternative that I would not hesitate to use.

Frequently Asked Questions (FAQ)

Conclusion

So, after years of building, breaking, and fixing, here is my final analysis for you. The “better” product is the one that’s correct for your specific job.

You should buy Loctite 222 (Purple) if you work with anything small and delicate. If you’re a gunsmith, an RC hobbyist, a computer builder, or you’re working with carburetors or any fastener under 1/4″ (M6), 222 is your best friend. It gives you the “peace of mind” that your screws won’t vibrate loose, without the “panic” that you’ll strip them when you need to take them out.

You must buy Loctite 243 (Blue) if you are doing any serious mechanical work. If you’re working on a car, a motorcycle, a lawnmower, or any piece of machinery with bolts 1/4″ (M6) or larger, this is your go-to. It is the workhorse. Its ability to cure on “as-received” oily bolts makes it the most reliable and user-friendly product in the real world. This is the bottle that should be in everyone’s main toolbox.

For me, the answer is simple: I own both. And after reading this, you probably know exactly which one you need for the project you have in front of you.