Loctite 242 Vs 222: Which One Is Better?

I’ve snapped my fair share of bolts. The first time I used the wrong threadlocker, I learned a painful, time-consuming lesson about strength ratings. Staring at the blue Loctite 242 and the purple Loctite 222, they seem similar, but they’re worlds apart in function. I’m here to break down my experience with both, from an analytical, hands-on perspective. My goal is to help you figure out which one you actually need for your project so you don’t make the same mistakes I did.

A Brief Comparison Table

My Experience With Loctite 242

Loctite 242 is the “classic” in my toolbox.

For years, it was the only threadlocker I bothered to buy.

It’s the bottle I reach for when I’m working on my car, my motorcycle, or even heavy-duty equipment around the house.

My first real “aha” moment with 242 was when I was reassembling the brake calipers on my old truck.

I knew those bolts were critical, and I knew they were subject to constant, heavy vibration.

Applying that drop of blue liquid gave me a profound sense of “bolt-it-and-forget-it” peace of mind. It cures into a solid, tough polymer that just plain works. You feel it when you go to remove it; you put your wrench on the bolt, give it a good pull, and there’s a satisfying “crack” as the bond breaks. It’s never failed me. It has held on engine mounts, handlebar clamps, and chassis bolts, all without vibrating loose. It’s the workhorse, the reliable default, and the product I learned to trust first.

Pros Of Loctite 242

• The Goldilocks Strength: This is the absolute biggest selling point. Loctite 242 is a medium-strength threadlocker.¹ This means it’s the perfect “just right” balance for 90% of the threaded fasteners on a vehicle or piece of machinery. It’s strong enough to prevent a bolt from backing out due to heavy vibration, which is its entire purpose. Whether it’s a bolt on a rattling engine cover, a lawnmower blade, or a bicycle crank arm, the 242 ensures it stays torqued and stays put, providing a massive safety and reliability benefit. I’ve used it to end persistent, annoying rattles that I could never solve otherwise.
• Removability With Hand Tools: Despite its “Goldilocks” strength, it’s not permanent. This is the crucial distinction between it and its red-bottled cousins (like Loctite 271). You do not need a blowtorch to get a 242-treated bolt off. A standard socket wrench or box-end wrench with a good bit of leverage is all you need. You’ll feel a distinct “snap” as the polymer bond breaks, and then the bolt will unthread normally. This serviceability is non-negotiable for components you will eventually need to maintain, like brake calipers, water pumps, or any accessory you might upgrade later.
• Excellent Fastener Size Range: The 242 formulation is designed to be optimal for fasteners ranging from 1/4″ (M6) up to 3/4″ (M20). This size range covers the vast majority of bolts and nuts you’ll encounter in automotive, marine, and power-sport applications. This versatility is what makes it such a great “general purpose” product. You don’t need to second-guess yourself. If the bolt is holding something important and it’s between the size of your pinky and your thumb, 242 is almost certainly the right call.
• Good Vibration Resistance: This is the core of its value proposition. Anaerobic threadlockers don’t just “glue” the threads; they cure in the absence of air to fill 100% of the microscopic gap between the male and female threads.² This solid polymer matrix makes it impossible for the fastener to “jiggle” or “walk” loose, even under severe harmonic vibration, like from a single-cylinder engine or an unbalanced rotating assembly. It also helps prevent fretting corrosion by sealing out moisture.

Cons Of Loctite 242

• Way Too Strong For Small Fasteners: This is the most important lesson I ever learned about 242, and it’s the entire reason 222 exists. If you use medium-strength blue threadlocker on a tiny M3 or M4 screw (like a small set screw or a screw holding a computer component), you are asking for trouble. The breakaway torque required to break the 242’s bond will be higher than the shear-strength of the screw head itself. I have personally snapped the head right off a small Allen bolt trying to remove it, turning a 5-minute job into a 2-hour-long extraction nightmare.
• Requires Significant Removal Force: The fact that it’s “removable with hand tools” is a pro, but it’s also a con in some contexts. You will need a proper tool. You cannot undo a 242-treated bolt with your fingers or with a low-torque, precision screwdriver. This makes it completely unsuitable for any fastener that you might need to adjust frequently or service in the field with a limited toolset. If you need to make fine-tuned adjustments, 242 will fight you every step of the way.
• Not Ideal For Plastic: This is a critical safety warning. Standard anaerobic threadlockers like 242 can be “too active” for certain thermoplastics. They can cause plastics (especially polycarbonate, common in clear guards or housings) to become brittle, develop “crazing” (spiderweb cracks), and ultimately fail catastrophically. You must use a “plastic-safe” threadlocker or a different fastening method for these applications.
• Cure Time and Cleanliness: While 242 is pretty robust, it’s not magic. It works best on clean, dry threads. People who just slop it onto a greasy, oily bolt and wonder why it backed out again are misusing the product. It has some oil tolerance (the newer Loctite 243 is even better at this), but for a reliable bond, you should hit the threads with brake cleaner first. It also requires a full 24 hours to reach 100% of its cure strength, which requires patience that not allDIY-ers have.

My Experience With Loctite 222

My discovery of Loctite 222 was born directly from the failure of 242.

After I snapped that tiny M3 bolt on an electronic enclosure, I went searching for a “weaker” solution.

I’ll admit, I was skeptical at first. “Low strength?

What’s the point?” It felt like buying “decaf” threadlocker.

Then, I started using it on my RC hobby parts.

These are all tiny M2.5 and M3 screws, usually threaded into aluminum.

Vibration is a massive problem, and the screws are constantly backing out. But if I used 242, I’d either snap the screw or strip the hex head. Loctite 222 (the purple one) was the revelation. It provided just enough “drag” or “damping” to keep the screws from vibrating loose, but I could still easily remove them with a small hex driver without any fear of breakage.

It’s not a “locker” in the same way 242 is. I think of it as a “vibration damper” for delicate threads. I now use it on anything small and delicate: set screws in a control knob, calibration screws on a carburetor, or screws for mounting a scope to a firearm. It’s a precision tool, not a blunt instrument.

Pros Of Loctite 222

• Protects Small, Delicate Fasteners: This is its entire mission. It is specifically formulated for low-strength applications on fasteners 1/4″ (M6) and smaller. Its low breakaway torque means you can remove that tiny M3 set screw without stripping the hex head or snapping the screw. It’s the only choice for small, precision assemblies like in electronics, hobby-grade RC cars, firearms (scope mounts, sight adjustments), and instrumentation. It gives you vibration-proofing without the risk of permanent, destructive assembly.
• Ideal For Softer Metals: This is a huge, often-overlooked benefit. When you are threading a steel screw into a softer material like aluminum, brass, or even some high-density plastics, you run a massive risk of stripping the female threads if you have to apply 242-levels of breakaway torque. Loctite 222 is gentle enough that it almost never puts the base material’s threads at risk. It’s my default choice for any screw going into an aluminum block, period.
• Perfect for Adjustable Components: Think of any screw that is used for calibration. A carburetor air/fuel mixture screw, a set screw that aligns a gear, or a limit-adjusting screw. These components need to stay in one place, but you must be able to adjust them later. Loctite 222 is the perfect solution. It adds just enough resistance to hold the screw’s position against vibration, but it’s easily overcome with a simple screwdriver when you need to make that fine-tuned adjustment.
• Easy, Non-Destructive Removal: You can remove 222-treated fasteners with the same small hand tools you used to install them.³ A small Allen key, a jeweler’s screwdriver, a non-marring tool—all will work. This is a massive pro. You don’t need to “plan” for removal. You don’t need to worry about having a big breaker bar. It’s designed for parts that need to be both secure and serviceable, a combination that 242 just can’t offer for this small scale.

Read more: My Thoughts on CCIYU Auto Parts

Cons Of Loctite 222

• Dangerously Under-Powered For Structural Bolts: This is the most critical con. If you use Loctite 222 on your brake calipers, suspension bolts, or any fastener larger than 1/4″ (M6), you are creating a dangerous situation. It simply does not have the shear strength to prevent a medium or large bolt from backing out under load and vibration. It will fail. It is not “better than nothing” in this context; it’s a false and dangerous sense of security.
• Completely Ineffective On Large Fasteners: Even in a non-structural application, using 222 on a 1/2″ bolt is a total waste of money. The surface area and mechanical forces at play are far too great for its low-strength formulation. It would be like trying to stop a car by dragging your feet. It just won’t work. It’s designed for small fasteners, and it only works on small fasteners.
• Potential To Cure Slower: Like all anaerobic threadlockers, its cure speed is affected by the material. It’s designed to cure, but on very “passive” metals like stainless steel or on non-metallic surfaces, the cure can be very slow or may not reach full strength without the use of a primer. This can be frustrating if you’re in a hurry, as you may think the product is “not working” when it just hasn’t had time or the right conditions to set up.
• Price For “Less” Product: A 10ml bottle of 222 often costs just as much as a 10ml bottle of 242. It can feel like you’re paying the same money for a “weaker” product. This is a psychological hurdle. You’re not paying for “strength”; you’re paying for “precision” and “removability.” But for the person who only buys one bottle, it can feel like a bad value compared to the do-it-all blue bottle next to it on the shelf.

Maintenance Tips For Loctite Products

• Cleanliness Is The Number One Rule: I cannot stress this enough. These products are chemicals, not magic. They are designed to work on clean, dry, oil-free metal. Before you apply a single drop, you must clean both the male (bolt) and female (hole) threads. I use a spray can of brake cleaner and compressed air. If you apply threadlocker to oily, dirty threads, you will get an inconsistent, weak bond that will likely fail. This is the number one reason people claim “it didn’t work.”
• Use An Anaerobic Primer (Sometimes): This is the pro-level tip. Anaerobic threadlockers cure by “curing” in the absence of air, and this reaction is catalyzed by metal ions.⁴ “Active” metals like iron and steel cure it fast. “Passive” metals like stainless steel, aluminum, titanium, and zinc-plated surfaces cure it very slowly. If you are working with passive metals or in cold temperatures (below 50°F / 10°C), use a primer like Loctite 7649. It’s an accelerator that ensures a fast, reliable, full-strength cure, and I swear by it for critical aluminum components.
• Proper Application Technique: Less is more. You do not need to “paint” the threads. For most fasteners, one or two drops is all you need. The technique also matters. For a through-hole (where the bolt goes all the way through a nut), apply the drop to the leading threads of the bolt. For a blind hole (where the bolt threads into a block), apply the drop into the bottom of the hole. This ensures that as the bolt is threaded in, the liquid is forced up the threads, coating them completely, rather than being pushed back out.
• Respect The 24-Hour Full Cure: This requires patience. Your fastener will get “fixture tight” (meaning it won’t move) in about 10-20 minutes. But it will not reach its full, advertised breakaway torque strength for a full 24 hours. If you apply threadlocker to a critical component and then immediately put it into heavy service (like starting a vibrating engine), you are not letting the product do its job. Assemble it, torque it to spec, and then let it sit overnight.
• Correct Storage Is Critical: You may notice that Loctite bottles are only half-full. This is intentional. The product is anaerobic, meaning it cures without air.⁵ The “headspace” in the bottle contains the air (oxygen) that keeps the liquid stable and prevents it from curing. Never, ever transfer threadlocker to a different, smaller, or sealed container, as it will turn into a solid brick. Store the original bottle in a cool, dry place out of direct sunlight.

Read more: Comparison Of Leatherman Free T2 And Victorinox

Comparison With Other Brands

• Permatex Is The Main Competitor: In almost any auto parts store, you’ll see Loctite (made by Henkel) and Permatex.⁶ They are the Coke and Pepsi of the threadlocker world. Permatex’s Medium Strength Threadlocker BLUE is the direct equivalent to Loctite 242.⁷ Permatex’s Low Strength Threadlocker PURPLE is the direct equivalent to Loctite 222. From a hands-on, real-world perspective, I have used both brands interchangeably for years and have found zero discernible difference in performance. They use the same chemistry, the same color-coding, and have the same strength ratings. My advice is to buy whichever one is on sale.
• Vibra-Tite And Other Brands: You may also see other brands like Vibra-Tite. Their product naming is a bit different, but they also follow the color-coding. Vibra-Tite 111 is their Low Strength Purple (222 equivalent), and Vibra-Tite 121 is their Medium Strength Blue (242 equivalent).⁸ Again, these are professional-grade anaerobic adhesives that function in the same way. I’ve had good experiences with them, but they are less common at the retail level. Many store-brands (like from NAPA or O’Reilly) are often just “white-label” products made by one of these major chemical companies, like Permatex, and are perfectly fine to use.
• Where Loctite Differentiates: Specialty Products: Where Loctite really has the market cornered is in its massive catalog of specialty products. For example, Loctite 243 is the “upgraded” version of 242.⁹ It’s also a medium-strength blue, but it’s specifically formulated to be more tolerant of oil on threads and to cure better on passive metals without a primer. This is a subtle but important difference in a professional or high-production setting. When comparing brands, you have to make sure you’re comparing the right products—242 vs. Permatex Blue, or 243 vs. Permatex High-Performance Blue.
• The Gel And Tape Formulations: Both Loctite and Permatex have innovated beyond the liquid. They now offer their threadlockers in a “gel” (which looks like a tube of chapstick) or a semi-solid “tape” form. These are fantastic for overhead applications where a liquid drop would be messy and drip. I keep a stick of blue in my mobile toolbox. The performance is the same; you are just paying for the convenience of the different application method. This is often a more significant factor in my purchasing decision than the brand name itself.

Frequently Asked Questions (FAQ)

Conclusion: For Loctite 242 And Loctite 222

So, after all of this, which one is “better”? My analytical, hands-on conclusion is that this is the wrong question. It’s like asking if a screwdriver is “better” than a socket wrench.

My initial mistake was thinking Loctite 242 (blue) was a one-size-fits-all solution. It’s not. It’s the “better” product for 90% of the bolts on your car, but it’s the wrong product for the tiny screws on your electronics. Loctite 222 (purple) is the “better” product for those delicate fasteners, but it’s dangerously wrong for your car’s suspension.

The “better” approach, and the one you should take, is to own both. I now have a bottle of 242 and 222 in my cabinet. Using the right tool for the job is the mark of a true professional or a smart DIY-er. You wouldn’t use a sledgehammer to hang a picture, so don’t use medium-strength threadlocker on a tiny, low-torque screw.