Thread Locker vs Thread Sealant: Which One Should You Buy?

GarageToolHQ earns a commission when you buy through links on our product pages, at no extra cost to you. Read our affiliate disclosure.

Below: the direct answer in full, what the listings state about strength, setting time and removal, the gear covered in this guide, and how to choose between a locker and a sealant without guessing at a figure the listing does not state.

Thread locker vs thread sealant: the direct answer

A thread locker is made to stop a fastener from loosening. The listings describe it locking nuts, bolts and fasteners in place, preventing loosening caused by vibration on engines, machinery and vehicles, and protecting threads from rust and corrosion. A thread sealant, by contrast, is made to seal a threaded joint so fluid does not leak past the threads. The Permatex listing in this guide bridges the two ideas: it is a medium strength thread locker that is also described as having thread sealant properties that reduce leaks and corrosion with a tight seal, and as ideal for a job needing pipe thread sealant.

That overlap does not make the two products the same. In this guide, a locker is judged on holding power and on how it comes apart later, while a sealant would be judged on sealing a joint that must stay leak-free. Read the listing for the job in front of you: strength, setting time, removal method and the fastener sizes stated are the figures that decide which product fits.

What the listings state

All four products in this guide are thread lockers, in blue medium strength or red high strength forms. Two listings state setting times, two state removal methods, and all four state a size or a fastener range. The table keeps those figures per product, because strength and removal differ from listing to listing.

The table shows the key trade in this category. A permanent red locker holds with high strength and needs heat for removal after setting, while the Permatex medium strength blue locker in this guide is described as removable with hand tools, which suits a joint that will need maintenance later. Where a listing does not state a setting time or a removal method, this guide leaves it as not stated rather than borrowing a figure from another product.

The gear in this guide

Loctite Threadlocker Red 271, 6 ml. This is the permanent, high strength option in the guide. The listing describes it locking and sealing metal fasteners, preventing loosening from vibration on engines, machinery and vehicles, and protecting from leaks, rust and corrosion. It sets in 10 minutes and is fully set in 24 hours, and it is only removable after setting by heating parts up to 500°F, given as 260°C. It is described for threads for nuts and bolts up to 1 inch, given as 25mm.

Loctite 243 Blue, 50 ml. This is a general-purpose, medium strength blue thread locker, given as 1.69 Ounces and 50 mL, for a 3/4 inch thread in the listing title. The listing notes improved oil tolerance and oil-tolerant setting on as-received fasteners without cleaning. No setting time and no removal method are stated for this product, so neither figure is claimed here.

Hannaera Thread Lock Blue and Red, 50 mlx2. This pack pairs a blue medium strength locker with a red high strength locker, in a 100ml total size across the two bottles. The listing describes strong adhesion for screws, nuts and metal fasteners to prevent loosening due to vibration, and sealing and leakage prevention from close contact in place of a solid gasket. Use is described as applying the locker evenly to the thread, tightening the nut, with an initial set in 20 minutes and a full set within 24 hours. Applications named in the listing include a valve cover, a water pump, automotive and industrial work, and furniture screws.

Permatex 24240 Medium Strength Blue, 36 ml. This medium strength blue locker is described as sealing and preventing loosening due to shock and vibration, and protecting threads from corrosion. It is stated for bolts from 1/4 inch to 3/4 inch, given as 6mm to 20mm, with applications named including valve cover bolts, water pump bolts, oil pan bolts, drive shaft bolts, rocker arm adjustment nuts, carburetor studs and intake manifold bolts. Unlike a permanent option, it is described as removable with hand tools, which suits maintenance and adjustment work, and it is described as having thread sealant properties that reduce leaks.

How to choose between a locker and a sealant

Start with the problem the joint has. If the problem is a fastener that loosens from vibration, a thread locker in the strength the listing states is the product described for that job, with the Permatex medium strength locker described as removable with hand tools for joints that will need maintenance later, and the Loctite high strength permanent red locker, which will need heat for removal after setting, for joints that are meant to stay put. If the problem is a threaded joint that must not leak, look for a sealant listing that states sealing for that joint, and read its stated thread size and setting details rather than assuming a locker will seal it.

Then check the fastener range, the size in the listing, and the removal method before buying. A locker stated for bolts up to 1 inch is not the same claim as a locker stated for bolts from 1/4 inch to 3/4 inch, and the Loctite red locker, which needs heat for removal after setting, is a different commitment from the Permatex blue locker, which comes apart with hand tools. Where a listing does not state a figure, treat it as not stated and check the manual for the equipment the joint belongs to.

FAQ: garage tools

What is thread locker?

On the evidence of these listings, thread locker is a liquid applied to a thread that locks a nut, bolt or fastener in place and prevents loosening due to vibration. The listings also describe it sealing fasteners and protecting threads from leaks, rust and corrosion.

How does thread locker work?

The Hannaera listing describes the method as applying the locker evenly to the thread and tightening the nut before it sets. Setting times stated are: Hannaera states an initial set in 20 minutes and a full set within 24 hours, while Loctite Red 271 states setting in 10 minutes and a full set in 24 hours. No other working mechanism is stated in these listings, so none is claimed here.

How much thread locker should be used?

No quantity per bolt is stated in these listings, so this guide does not state one. The Hannaera listing describes applying the locker evenly to the thread before tightening the nut, and that even application is the only amount guidance stated here.

Is thread locker glue?

The listings do call it screw glue: Loctite Red 271 is titled as a screw glue, and the Hannaera listing calls its product screw glue. Its job in these listings, however, is locking fasteners against vibration and sealing threads, not general gluing, so it should be chosen as a fastener locker rather than as an ordinary adhesive.

How is thread locker cleaned off a bolt?

No cleaning method is stated in these listings, so none is given here. Removal after setting is stated in two listings: Permatex medium blue is described as removable with hand tools, while Loctite Red 271 is described as only removable after setting by heating parts up to 500°F, given as 260°C.

Related: our engine and shop equipment hub for more garage gear guides.