Loctite Product Guide

Loctite anaerobic adhesives cure in the absence of air when in contact with metal. Choosing the wrong grade is one of the most common fastener mistakes in the workshop - using red where blue was needed, or threadlock where a retaining compound was required. This guide covers the most common grades used in automotive and motorsport engineering.

Important: Always degrease surfaces before applying any Loctite product. Active metals (copper, brass) and passive metals (aluminium, stainless, titanium) cure at different rates - passive metals benefit from an activator primer. All temperature ratings are for continuous exposure. Verify suitability with Henkel's datasheet for critical applications.

Colour Reference

Purple - Low strength, small fasteners

Blue - Medium strength, removable

Red - High strength, permanent

Orange - Flange sealant / gasket maker

Green - High strength retaining / wicking / large threads

White - Pipe & thread sealants

Cream/Yellow - Hydraulic & pneumatic pipe sealants

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Threadlocking Grades

Product	Colour	Strength	Thread Size	Max Temp	Removable?	Notes & Use Cases
222 Low Strength Threadlock	Purple	Low	M1 – M6	150°C	Removable	Instrument screws Sensor fittings Delicate/fine threads Adjuster screws
243 Medium Strength Threadlock	Blue	Medium	M6 – M20	150°C	Removable	General fasteners Suspension bolts Brake caliper bolts Sump plugs Most service items
263 High Strength Threadlock	Red	High	M6 – M20	150°C	Permanent	Wheel studs Differential bolts Engine mount bolts Permanent structural fasteners
270 High Strength Threadlock	Green	High	M20+	150°C	Permanent	Large studs Heavy structural bolts Industrial fasteners
290 Wicking Grade Threadlock	Green	Medium-High	M4 – M16	150°C	Wicking	Applied post-assembly Wicks into thread by capillary action Loose fasteners in situ Porosity sealing

Pipe & Thread Sealants

Pipe sealants fill thread voids to prevent fluid or gas leakage. Unlike threadlocks, they are designed to seal rather than lock - removal torque is typically lower.

Product	Colour	Strength	Application	Max Temp	Notes & Use Cases
542 Thread Sealant	Red	Medium	Hydraulic fittings	150°C	Hydraulic line fittings Pneumatic connectors High-pressure sealing Metal-to-metal threads
572 Pipe Sealant	White	Medium	Coarse metal fittings	150°C	Coarse tapered threads Slow cure allows alignment Water & gas systems
577 Medium Strength Pipe Sealant	Cream/Yellow	Medium	Hydraulic & pneumatic	150°C	Hydraulic system fittings Pneumatic connections NPT & BSPT threads Standard workshop sealant
5331 Low Strength Pipe Sealant	White	Low	Plastic fittings	100°C	Plastic to plastic Metal to plastic threads Low-pressure sealing

Flange Sealants & Gasket Makers

Flange sealants form a cured-in-place gasket between rigid metal mating faces. They fill surface imperfections and eliminate the need for a conventional cut gasket on many joint types. Unlike pipe sealants, they are applied to flat or near-flat surfaces rather than threads.

Product	Colour	Strength	Application	Max Temp	Notes & Use Cases
574 High Strength Flange Sealant	Orange	High	Rigid metal flanges	150°C	Sump rails Timing covers Water pump flanges Gearbox casings Pump housings Oil and coolant resistant Replaces cut gaskets on rigid joints

Retaining Compounds

Retaining compounds bond cylindrical slip or press fits - bearings into housings, bushes into bores, shafts into hubs. They fill the gap between surfaces to eliminate fretting and increase load capacity. Gap size is critical: choose the wrong grade and it won't cure fully.

Product	Colour	Strength	Max Gap	Max Temp	Notes & Use Cases
620 High Temp Retaining Compound	Red	High	0.10 mm	200°C	Exhaust manifold studs High-temp bearing retention Engine components near heat sources
638 High Strength Retaining	Green	High	0.25 mm	150°C	Larger clearance fits Bush retention in worn housings Keyless shaft-to-hub assemblies
648 High Strength Retaining	Green	High	0.15 mm	175°C	Bearing retention - standard choice Bush retention Gear/pulley to shaft Eliminates fretting corrosion
680 High Strength Retaining	Green	High	0.08 mm	150°C	Close-tolerance fits Precision bearings High-speed rotating components

Motorsport Applications

Engine

Sump, Timing Cover & Water Pump

574 replaces cut gaskets on rigid metal-to-metal joints. Apply a thin bead to the clean dry flange face, assemble within 10 minutes, and allow to fully cure before adding fluids. Oil and coolant resistant once cured.

- Loctite 574 (Orange Flange Sealant)

Suspension & Brakes

Suspension Fasteners

Wishbone bolts, damper mounts, anti-roll bar links. Vibration and load cycling makes threadlock essential, but removability is required for geometry adjustment.

→ Loctite 243 (Blue)

Drivetrain

Wheel Studs & Diff Bolts

Permanent fixing on high-load fasteners that will not need routine removal. Red grade for the torque capacity and permanence required.

→ Loctite 263 (Red)

Engine

Exhaust Manifold Studs

Continuous temperatures well above standard Loctite limits. The 620 red retaining compound is rated to 200°C continuous and handles thermal cycling.

→ Loctite 620 (Red Retaining)

Engine

Bearing & Bush Retention

Camshaft bearing caps, gearbox input shaft bearings, con-rod small-end bushes. 648 is the default choice for clearances up to 0.15mm.

→ Loctite 648 (Green Retaining)

Hydraulics

Brake & Clutch Line Fittings

Hydraulic system fittings need thread sealing rather than locking. 542 handles high-pressure metal fittings; 577 for lower-pressure NPT/BSPT connections.

→ Loctite 542 or 577

In-situ Repair

Loose Fasteners Already Assembled

When you can't disassemble to apply threadlock - 290 wicks into the assembled joint by capillary action. Green colour, apply to the thread gap and allow to wick through.

→ Loctite 290 (Green Wicking)

Application Tips

Degrease threads thoroughly before application - oils and grease prevent curing. Isopropyl alcohol is adequate for most applications.
Passive metals (aluminium, stainless, titanium) cure slowly without a primer activator. Use Loctite 7471 or 7649 primer for reliable cure times on these materials.
Apply to the male thread only, 2-3 threads from the end. This prevents contamination of the assembly when the fastener is tightened.
Fixture time (handling strength) is typically 10-20 minutes at 22°C. Full cure takes 24 hours. Temperature accelerates cure; cold slows it significantly.
To remove permanent grades: heat to 250°C and apply removal torque while still hot. Impact tools often work on medium grades without heat.
Do not mix grades on the same fastener. Removing residual cured Loctite before reapplication prevents adhesion failure.
For retaining compounds, apply to both the bore and the shaft/outer race for best results. Assemble immediately and avoid rotation during cure.
Shelf life is typically 12-24 months from manufacture. Partially cured product in the bottle indicates contamination or age - discard.

Disclaimer: Product data compiled from Henkel Loctite technical datasheets. Specifications are subject to change - always verify against the current datasheet for critical applications. EBD accepts no responsibility for incorrect product selection.

→ Also see: Bolt Torque Reference → Metric Thread Data