Loctite 243 Blue Medium Strength Threadlocker 50 mL (1.69 fl oz) — Oil-Tolerant, Removable Hold for Bolts up to 3/4"

Loctite 243 is a medium-strength blue threadlocker designed to lock and seal threaded fasteners while tolerating light oil contamination.

Engineered for general-purpose assembly, this 50 mL (1.69 fl oz) bottle of Loctite 243 offers a balance of secure holding and future serviceability. Its formulation cures anaerobically to form a durable bond that resists vibration and loosening, yet allows disassembly with standard hand tools. Improved oil tolerance means the product can often cure on as-received fasteners without time-consuming degreasing in non-critical applications.

How does Loctite 243 prevent loose fasteners in vibrating assemblies?

Loctite 243 fills the gaps between mating threads, creating a polymer barrier that resists vibration-induced rotation and fretting. Once cured in the absence of air, the adhesive maintains clamp force and reduces the risk of nuts and bolts backing out under cyclic loads.

• Medium strength suitable for maintenance and repair tasks
• Adheres to metal threads to stop micro-motion
• Works on bolts up to 3/4" thread diameter
• Reduces need for mechanical locking devices in many applications

Can I apply it to oily or unclean fasteners?

Loctite 243 has improved oil tolerance, so it can often cure on lightly contaminated or as-received parts without an aggressive cleaning step. For best performance in critical assemblies, remove heavy grease, oils, or coatings to ensure maximum bond strength and predictability.

• Formulated to cure with some surface oil present
• Recommended to clean heavily contaminated parts when possible
• Speeds up maintenance where cleaning time is limited
• Not intended as a substitute for proper surface preparation in safety-critical joints

How strong is the bond and how do I remove fasteners later?

This medium-strength threadlocker secures fasteners while still allowing disassembly with typical tools and hand torque. Heat and hand tools are generally sufficient to break the cured adhesive when service or replacement is required, making it practical for maintenance routines.

• Designed for removable assemblies—holds under load but allows later disassembly
• Can be loosened with standard wrenches; heat may aid stubborn parts
• Suitable where periodic maintenance access is expected
• Not as permanent as high-strength formulations intended for one-time assemblies

Who is this product for? Loctite 243 is aimed at technicians, repair shops, and DIY enthusiasts who need a reliable, reusable threadlocker for general mechanical work. It fits applications ranging from automotive and industrial maintenance to consumer repairs where a medium-strength, oil-tolerant solution is preferred. The 50 mL size is convenient for bench use and periodic maintenance, offering a practical balance of performance, reusability, and handling for routine fastening tasks.