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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallThere is no universally correct thread sealant for every aluminum cylinder head or head bolt. Permatex High Temperature Thread Sealant is one candidate to check because its manufacturer lists “head bolts into through holes” as a suggested application—but that does not establish compatibility with every engine or bolt position. Follow the service manual for the exact engine and fastener before selecting or applying any compound.
First determine whether the bolt needs sealant
Check the exact fastener location in the engine’s service manual. The key question is whether its threaded hole opens into a coolant or oil passage, and whether the manufacturer specifies sealant there. A head bolt that enters a fluid passage may need a sealing compound; a bolt in a blind hole may have a different assembly requirement. The product pages available here do not identify the requirements for any particular engine, so they cannot replace the applicable service procedure.
Do not use thread sealant as a remedy for a head-gasket leak. These products are intended for threaded connections and fittings, not for repairing a failed gasket or sealing a leak elsewhere in the engine.
Compare the manufacturer-stated options
These are product specifications and suggested uses, not independent comparative test results. A pressure figure alone cannot establish which compound is best: the cited materials do not provide comparable test methods and conditions.
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#1 Best Overall
- OEM-Approved Performance: LOCTITE automotive products are not only OEM-specified but also designed and tested by leading auto manufacturers. Trusted by professionals in engine building and repair worldwide (PN: 1158514)
- Dependable Sealing: Provides lubrication for fasteners during assembly, ensuring a smooth and effective installation
- Strong Resistance: Seals gaps between threads to prevent premature loosening, maintaining a secure fit over time
- Corrosion Prevention: Protects against corrosion, facilitating easier disassembly in the future and reducing maintenance issues
- Versatile Applications: Ideal for a variety of uses, including head bolts, water pump bolts, thermostat housings, intake manifold bolts, and temperature sensors
| Product | Manufacturer-stated use and compatibility | Specifications and limits |
|---|---|---|
| Permatex High Temperature Thread Sealant | Suggested for “head bolts into through holes,” as well as oil-pressure sensors, oil and coolant lines, fuel fittings, and other metal fittings. | Contains PTFE; stated operating range is −65°F to 400°F (−54°C to 204°C). A listed use does not prove fit for every head-bolt position. Permatex product information. |
| Permatex High Performance Thread Sealant | Suggested for head bolts into through holes and oil or coolant lines; formulated for metal tapered pipe threads. | Its technical data sheet says it cures to withstand 10,000 PSI within 24 hours. Permatex does not provide a comparable test basis here for ranking it against the other products. Permatex product information. |
| Permatex Seal & Lock Thread Compound | Permatex says it works on steel, aluminum alloys, brass, and copper, and suggests it for coolant-temperature sensors and other fluid-system fittings. The cited page does not specifically list head bolts. | Combines sealing and locking behavior; the product page states a 1,000 PSI sealing claim and says it is removable with hand tools. Its instructions specify 72 hours to full strength. Product page and instructions. |
| Permatex Thread Sealant with PTFE | The technical data sheet describes a paste for pipes, fittings, and threaded connections in air, oil, gas, and hydraulic systems. It does not specifically list head bolts. | The sheet states up to 5,000 PSI and an operating range of −65°F to +300°F (−54°C to +204°C). Permatex technical data sheet. |
| LOCTITE 567 | Described as an anaerobic sealant for metal pipe and fitting threads; aluminum is among the compatible metals. The cited page does not specify cylinder-head bolts. | Listed operating range is −55°C to 200°C (−65°F to 400°F). LOCTITE product information. |
The manufacturer pages and data sheets cited above do not state calendar publication years for these specifications. Treat them as the manufacturers’ claims, not as independently verified comparative results.
How to choose when the service manual permits options
- Match the stated use. A product specifically suggested for head bolts into through holes is more directly relevant to that application than one described only for pipes and fittings; neither description overrides the engine manual.
- Check the materials and fluids. Confirm manufacturer guidance for the relevant metals and the fluid at the joint, such as coolant or oil. Aluminum compatibility for a fitting does not by itself establish suitability for a cylinder-head bolt.
- Consider compound behavior. Some products seal; Seal & Lock is described as both sealing and locking. Whether thread-locking behavior or later removability is appropriate depends on the engine’s assembly procedure.
- Follow the specific temperature, pressure, application, and cure guidance. Published claims are not interchangeable ratings. Do not select a product by PSI alone when the data sheets do not establish comparable test conditions.
If the manual allows a product in the relevant application, Permatex High Temperature Thread Sealant is a candidate to investigate because its manufacturer expressly lists head bolts into through holes. Confirm that the listing matches the exact fastener and follow both the engine and product instructions before use.
Rank #2
- APPLICATION: RectorSeal No.5 is a non-hardening, slow-drying thread sealant made from special inert fillers dispersed in an oleoresinous base to facilitate its application to threaded pipe connections
- SOFT SETTING: Our pipe thread sealant is a soft-set, slow drying compound which seals, lubricates, and protects threaded pipe and fittings and will not dry out in the container
- POTABLE WATER SEALANT: RectorSeal No.5 pipe dope thread sealant lubricates and protects pipe threads; contains no metal; permits easy break out with no damage to threads
- PIPE COMPATIBILITY: For pipe made of galvanized steel, iron, brass, copper, aluminum, stainless steel, polyethylene, reinforced fiberglass, and pvc. do not use on abs or cpvc; for natural gas and water lines up to 2" and pressure up to 100 psi, the piping system may be placed into immediate service; other services are recommended 24 hours after application
- FOR THE TRADESMAN: RectorSeal is recognized as a leading provider of quality solutions for the professional trades serving heating, ventilation, and air conditioning (HVAC/R), plumbing, electrical, and construction markets
Apply only the instructions for the chosen compound
Torque and assembly details must come from the engine’s service procedure and the selected product’s directions. Do not assume that instructions for one sealant apply to another.
For Permatex Seal & Lock specifically, the manufacturer directs users to knead the tube, apply compound to the leading male threads while leaving the first thread free, cover three quarters of a thread turn, assemble and tighten to the recommended torque, then allow 72 hours for full strength. Those directions are product-specific; they are not a general head-bolt procedure. For Permatex High Temperature Thread Sealant, the product page directs users to consult its technical data sheet for complete information.
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Best Value
- Stops block leaks
- Seals cracked cylinder heads and blocks
- Repairs blown head gaskets
- Dual Action 2 Part Formula — LIQUID CERAMIC: Liquid penetrates large and small leaks to form a seal actually harder than the original head gasket — REINFORCED FIBERS: Fiber additives lock together with liquid to increase strength and promote a permanent seal
- Head Gasket Sealant is NOT COMPATIBLE with antifreeze and must only be added to the cooling system after ALL ANTIFREEZE has been flushed and removed.
Rank #4
- Economical general-purpose fitting sealant
- Outperforms tapes and pipe dopes
- Seals and resists pressure in air, oil, diesel fuel and hydraulic systems
- Remains pliable at higher and lower temperatures
- Suggested Applications: Air conditioning fittings, temperature sending fittings, hydraulic fittings
Rank #3
- OEM-Approved Performance: LOCTITE automotive products are not only OEM-specified but also designed and tested by leading auto manufacturers. Trusted by professionals in engine building and repair worldwide (PN: 483629)
- Dependable Thread Sealing: Fast-curing formula withstands pressures up to 10,000 PSI, ensuring leak-proof, long-lasting seals in demanding conditions
- Versatile Alternative: Replaces traditional tapes, pipe dopes, and pre-coated parts, offering a superior solution for a variety of sealing needs
- Wide Application Range: Perfect for stainless steel fittings, head bolts in through holes, oil pressure sending units, sensors, oil and coolant lines, and more
- Specialized Formulation: Engineered specifically for metal and tapered pipe thread fittings, providing a reliable and durable solution for automotive professionals
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
