How we researched this guide
We compared 5 Permatex products for this guide, each checked against its Amazon listing record and Permatex technical data sheets where published. The Ultra Black figures come from its technical data sheet, including the 2-hour tack-free and 24-hour full-cure times and the minus 65 to 400 degree continuous range, and the Ultra Grey figures from its data sheet, including the 1-hour tack-free time and the gasoline-contact exclusion.
Owner evidence is drawn from listing summaries, paraphrased and tied to the product it describes, with the recurring lesson stated plainly: surface preparation and bead discipline decide the result more than the tube. We do not test sealants. Maker limits are printed as limits, including the head-gasket exclusion that applies to every RTV in this guide.
The 30-second answer
Buy Permatex Ultra Black first: it seals the oil pans, valve covers and transmission pans most beginners meet. Buy Ultra Grey for high-torque and import joints, Ultra Copper for turbo and exhaust-adjacent heat, The Right Stuff when the vehicle must return to service the same day, and Threadlocker Blue for bolts that vibrate loose but must stay removable. Never use any RTV here as a head gasket.
Best Overall
Permatex Ultra Black
The oil-resistant RTV for oil pans, valve covers and transmission pans. Best if a beginner buys one tube first.
Best for High-Torque Joints
Permatex Ultra Grey
The rigid, high-torque RTV for import engines and vibration-heavy assemblies. Best if the joint sees torque and shake.
Best for High Heat
Permatex Ultra Copper
The maximum-temperature RTV for turbo and exhaust-adjacent joints. Best if heat, not oil, is the enemy.
Best for Fast Return
Permatex The Right Stuff
The 1-minute gasket maker in a PowerBead can for jobs that cannot wait a day. Best if the vehicle must run soon.
Best for Fasteners
Permatex Threadlocker Blue
The medium-strength threadlocker that stops bolts loosening without freezing them. Best if the seal is on a thread, not a flange.
Quick compare: sealants side by side
| Product | Key figure | Best for | Check Price |
|---|---|---|---|
| Permatex Ultra Black | RTV, oil-resistant, to 400 F | First tube, oil-exposed joints | |
| Permatex Ultra Grey | RTV, rigid high-torque | Import and vibration-heavy joints | |
| Permatex Ultra Copper | RTV, maximum temperature | Turbo and exhaust-adjacent joints | |
| Permatex The Right Stuff | Instant gasket maker, can | Jobs that must run the same day | |
| Permatex Threadlocker Blue | Threadlocker, medium, removable | Bolts that vibrate but must stay serviceable |
Sealant finder: how fast must the vehicle return to service?
Enter the hours you can wait before the vehicle must run again. The finder routes only to products in this guide, and a job that cannot wait at all still gets The Right Stuff, never a dead end. Always confirm the application on the tube first.
How to choose a sealant as a beginner
Flange or thread: name the joint first
A flange joint, where two flat faces meet, needs a gasket maker like RTV. A threaded fastener, where a bolt must stay put but stay removable, needs threadlocker. Choosing by tube colour before naming the joint is the beginner error that causes most sealant failures, because the two products do not substitute for each other.
Fluid: what touches the seal
Oil, coolant, fuel and air all attack different chemistries. Ultra Black is built for oil resistance, Ultra Grey is excluded from gasoline contact, and threadlocker is built for threads, not fluids. Read the fluid the joint actually sees, then match the tube to that fluid, not to the shelf position.
Heat: read the joint temperature
An oil pan and a turbo joint live in different thermal worlds. Ultra Black covers to 400 degrees continuous, Ultra Copper is the high-temperature choice for turbo and exhaust-adjacent work, and guessing the temperature guesses the failure. If the manual gives a temperature, use it; if it gives a part number, match it.
Flex or rigidity: how the joint moves
Flexible joints need a flexible sealant, and high-torque joints need a rigid one. Ultra Black stays flexible through heat and vibration, Ultra Grey is deliberately rigid for high-torque assemblies, and swapping them trades one failure mode for another. The manual's colour or part number is the tie-breaker.
Cure time: plan the downtime honestly
Tube RTV needs hours to tack and a full day to cure, while The Right Stuff is built for fast return to service. A beginner who refills oil early, or torques a joint before it cures, creates the leak the sealant was bought to stop. Schedule the cure before opening the joint, not after.
Preparation: the step that decides everything
Every sealant in this guide fails on a dirty, oily or old-sealant-covered surface. Remove all old material, clean and dry the faces, apply a thin continuous bead, trace the bolt holes, and torque in sequence. Preparation is not a preliminary; it is the seal, and the tube only finishes it.
Application table: joint, product and limit
Each row is routed on maker applications and exclusions, not on habit. The last column is the limit that matters most for that row.
| Joint | Product in this guide | Limit to respect |
|---|---|---|
| Oil pan | Permatex Ultra Black | Full 24-hour cure before refilling |
| Valve cover, high torque | Permatex Ultra Grey | Not for gasoline-contact parts |
| Turbo or exhaust-adjacent joint | Permatex Ultra Copper | Not an exhaust gasket substitute |
| Work vehicle, same-day return | Permatex The Right Stuff | Preparation still mandatory |
| Vibrating bolt or bracket | Permatex Threadlocker Blue | Not a flange sealant |
| Cylinder head gasket | None in this guide | Use a head gasket; no RTV here qualifies |
Sealants by budget
| Tier | What you get | Example pick |
|---|---|---|
| First tube | One general RTV for the common jobs | Permatex Ultra Black |
| Second tube | A specialist for torque or heat | Permatex Ultra Grey or Ultra Copper |
| Fast jobs | Same-day return to service | Permatex The Right Stuff |
| Fasteners | Vibration-proof, serviceable bolts | Permatex Threadlocker Blue |
| Complete beginner kit | One of each job class | All five products in this guide |
Types: RTV, instant gasket maker and threadlocker
| Type | What it does | Best for |
|---|---|---|
| RTV silicone | Cures in air into a flexible or rigid rubber gasket | Flange joints: oil pans, covers, timing covers |
| Instant gasket maker | Forms a rubber gasket on assembly, fast return | Work vehicles and weekend jobs |
| Threadlocker | Locks a thread against vibration, anaerobically | Bolts and nuts that must stay serviceable |
| Not a sealant here | A specified gasket or a head gasket | Any joint the manual specifies a gasket for |
Detailed reviews: sealants for beginners
Each review below follows the same order: why it is our pick, its maker specs, where it fits, owner themes, who should not buy it, and what to pair it with.
Best overall: Permatex Ultra Black
Best Overall
Why the Permatex Ultra Black is our pick
Ultra Black is our first-tube pick because it covers the most common beginner jobs with the most forgiving chemistry: maximum oil resistance, high flexibility, sensor-safe and non-corrosive, in a formula Permatex describes as meeting the performance specifications of original-equipment silicone gaskets. Its temperature range runs from minus 65 degrees Fahrenheit continuous to 400 degrees, with 500 degrees intermittent, so it survives oil, heat and vibration on the joints beginners actually seal.
Permatex Ultra Black key specs
- Part number: Permatex 82180
- Type: RTV silicone gasket maker, oxime silicone
- Colour: metallic black
- Temperature: minus 65 to 400 F continuous, to 500 F intermittent
- Oil resistance: maximum (maker description)
- Sensor safe: yes; low odour, non-corrosive
- Tack-free time: 2 hours (technical data sheet)
- Full cure: 24 hours (technical data sheet)
- Typical uses: oil pans, transmission pans, valve covers, timing covers, differential covers
- Not for: cylinder head gaskets or head gasket sealing
- Container in this guide: 3.35 oz tube
- Maker: Permatex (ITW)
Permatex Ultra Black: fits and best for
Best for first-time gasket work on oil pans, valve covers, transmission pans, timing covers and differential covers on cars and trucks. It fits a beginner's toolbox as the default tube, and a winch owner's maintenance shelf as the sealant for differential and transmission covers opened during recovery-gear servicing.
Permatex Ultra Black pros and watch-outs
- Covers the most common beginner sealing jobs in one tube
- Maximum oil resistance for oil-exposed joints
- Sensor-safe and non-corrosive, so oxygen sensors are protected
- Stays flexible through heat and vibration cycles
- OEM-specified formula, not a generic silicone
- Needs a full 24 hours to cure; the vehicle cannot return to service at once
- Not a head-gasket product, despite beginner assumptions
- Bead size matters: too much sealant squeezes into oil passages
- Tube size is small for large jobs; buy the right size first
Permatex Ultra Black: what owners report
- Owner themes on the listing stress leak-free oil pans after careful surface preparation, with preparation, not the tube, named as the difference between success and a repeat leak.
- Beginner owner summaries repeatedly mention the same lesson: a thin, continuous bead beats a thick one, and excess sealant inside the joint causes more trouble than too little outside it.
- The recurring watch-out is cure time: owners who refilled oil early report weeping that a full cure would have prevented.
Permatex Ultra Black: who should not buy
Do not buy Ultra Black for a cylinder head gasket, an exhaust joint, or a joint that must return to service within the hour. Head gaskets need a head gasket, exhaust joints need a high-temperature product like Ultra Copper, and fast-return jobs need The Right Stuff in this guide.
Permatex Ultra Black: pair it with
Pair it with the Permatex Ultra Grey, which keeps the setup tidy and repeatable.
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Lay a practice bead on cardboard first; the bead you practise is the bead the joint gets. our winch maintenance checklist
Best for high-torque joints: Permatex Ultra Grey
Best for High-Torque Joints
Why the Permatex Ultra Grey is our pick
Ultra Grey earns its place because it is built for a different failure mode from Ultra Black: rigid, high-torque, vibration-resistant assemblies, especially on import engines, where a flexible sealant can be worked loose. Permatex describes it as a sensor-safe, low-odour, non-corrosive formula that meets original-equipment silicone specifications, in a grey non-sag paste that stays where a beginner puts it, with a tack-free time of about one hour.
Permatex Ultra Grey key specs
- Part number: Permatex 82194
- Type: RTV silicone gasket maker, oxime silicone rubber
- Colour: grey, non-sag paste
- Character: rigid, high-torque, vibration resistant
- Sensor safe: yes; low odour, non-corrosive
- Tack-free time: 1 hour (technical data sheet)
- Typical uses: high-torque and high-vibration assemblies, import engines
- OEM specified: yes, with OEM interchange numbers published
- Not for: parts in contact with gasoline (technical data sheet note)
- Not for: pure oxygen or oxygen-rich systems
- Container in this guide: 3.5 oz tube
- Maker: Permatex (ITW)
Permatex Ultra Grey: fits and best for
Best for valve covers, oil pans and timing covers on high-torque and high-vibration engines, particularly imports, where the maker specifies a rigid grey RTV. It fits a beginner who has already done one Ultra Black job and now faces a joint the manual calls out by colour or part number.
Permatex Ultra Grey pros and watch-outs
- Rigid formula resists working loose under torque and vibration
- Non-sag paste stays on vertical surfaces while a beginner works
- Sensor-safe for modern engines with oxygen sensors
- OEM interchange numbers published, so the manual match is checkable
- Faster tack-free time than Ultra Black
- Not for gasoline-contact parts, a limit beginners miss
- Rigidity is wrong for joints that need flex; do not use it everywhere
- Still needs full cure before the joint is loaded
- Colour-coding by manual matters; guessing the colour guesses the job
Permatex Ultra Grey: what owners report
- Owner themes on the listing centre on import valve covers and timing covers, where the grey formula matched the factory sealant and stopped repeat weeping.
- Beginner summaries praise the non-sag paste: on vertical covers it does not run while bolts are torqued in sequence.
- The watch-out repeated by owners is the same as for every RTV: old sealant not fully removed is the cause of the second leak, not the new tube.
Permatex Ultra Grey: who should not buy
Do not buy Ultra Grey for a flexible joint, a gasoline-contact part, or a job where the manual specifies a different colour. Rigidity is a feature only where the joint needs it; elsewhere it is the wrong tool, and the gasoline-contact exclusion is a hard limit.
Permatex Ultra Grey: pair it with
Pair it with the Permatex Ultra Black, which keeps the setup tidy and repeatable.
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Trace every bolt hole with the bead, then torque in sequence, or the seal fails at the holes. our winch motor repair guide
Best for high heat: Permatex Ultra Copper
Best for High Heat
Why the Permatex Ultra Copper is our pick
Ultra Copper is our high-heat pick because it is the only tube in this guide designed for the hottest joints a beginner meets: Permatex describes it as a maximum-temperature RTV for high operating temperatures, turbocharger applications and exhaust systems. Where Ultra Black and Ultra Grey are oil and torque products, Ultra Copper is a temperature product, and choosing it is a matter of reading the joint's heat before its fluid.
Permatex Ultra Copper key specs
- Part number: Permatex 81878
- Type: RTV silicone gasket maker, maximum temperature
- Colour: metallic copper
- Designed for: high operating temperatures, turbocharger applications, exhaust systems
- Sensor safe: maker RTV family trait; confirm on the tube for the application
- Container in this guide: 3 oz tube
- Maker: Permatex (ITW)
- Not a substitute for: exhaust gaskets where a gasket is specified
- Companion products in this guide: Ultra Black for oil, Ultra Grey for torque
- Beginner rule: heat first, then fluid, then flexibility
- Cure: follow the tube directions; do not shortcut cure on hot joints
- Warranty: Not published in the sources checked for this guide
Permatex Ultra Copper: fits and best for
Best for turbocharger and exhaust-adjacent joints and any sealing surface that runs hotter than an oil pan. It fits a beginner who has already learned RTV basics on a cool joint and now faces a hot one, and it fits as the second tube in a toolbox, never the first.
Permatex Ultra Copper pros and watch-outs
- Highest-temperature RTV in this guide for turbo and exhaust work
- Copper colour makes the joint's product choice visible on inspection
- Same RTV working method as the other tubes, so skills transfer
- Purpose-built, not a general tube stretched past its rating
- Wrong for ordinary oil pans; heat rating does not make it better everywhere
- Still an RTV, not an exhaust gasket where a gasket is specified
- Hot joints punish rushed cure more than cool ones
- Beginners must confirm the application on the tube, not assume copper means universal
Permatex Ultra Copper: what owners report
- Owner themes on the listing stress turbo and exhaust-adjacent use, where ordinary RTV had failed from heat and the copper formula held.
- The recurring beginner lesson in owner summaries is reading the joint first: buyers who chose by temperature, not by tube colour habit, report success.
- The watch-out is overreach: owners who used it as a universal sealant report no advantage over the cheaper correct tube, because heat was never the problem.
Permatex Ultra Copper: who should not buy
Do not buy Ultra Copper as your only sealant, or for an oil pan, a valve cover, or any joint where heat is ordinary. It is a specialist tube; the general jobs in this guide belong to Ultra Black, and buying the specialist first wastes its advantage.
Permatex Ultra Copper: pair it with
Pair it with the Permatex Ultra Black, which keeps the setup tidy and repeatable.
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Check the tube for the heat rating before an exhaust-adjacent job, not after it leaks. our winch cable replacement guide
Best for fast return to service: Permatex The Right Stuff
Best for Fast Return
Why the Permatex The Right Stuff is our pick
The Right Stuff earns its place because it solves the beginner's most common scheduling problem: the vehicle that must return to service before a 24-hour RTV cure finishes. Permatex sells it as a 1-minute instant rubber gasket maker in a 7.5-ounce PowerBead can, designed to make a gasket on assembly and return the joint to service far faster than a tube RTV. That speed changes which jobs a beginner can attempt on a weekend, but it does not change the preparation or the bead discipline.
Permatex The Right Stuff key specs
- Part number: Permatex 85224
- Type: instant rubber gasket maker
- Form: 7.5 oz PowerBead can
- Maker description: 1-minute gasket maker
- Colour: black (Right Stuff 1 Minute Black style)
- Use: formed-in-place gaskets where fast return to service matters
- Preparation: same as RTV — clean, dry, old sealant fully removed
- Bead discipline: continuous bead, bolt holes traced, as with tube RTV
- Not a substitute for: a specified gasket or a head gasket
- Container: pressurised can, not a squeeze tube
- Maker: Permatex (ITW)
- Warranty: Not published in the sources checked for this guide
Permatex The Right Stuff: fits and best for
Best for weekend jobs, fleet and work vehicles, and any joint where downtime costs more than the can, provided the application allows a formed-in-place gasket. It fits a beginner who has already learned bead control on a tube RTV and now needs speed, not a beginner's first-ever sealing attempt.
Permatex The Right Stuff pros and watch-outs
- Fast return to service versus a 24-hour tube cure
- PowerBead can lays a controlled bead without a caulk gun
- Same formed-in-place method as tube RTV, so skills transfer
- Useful for work vehicles where a day of downtime matters
- Pressurised can needs care in storage and handling
- Speed tempts beginners to skip surface preparation; do not
- Not the cheapest way to learn bead control
- Still not a head gasket or a specified-gasket substitute
Permatex The Right Stuff: what owners report
- Owner themes on the listing centre on fleet and weekend use: joints returned to service the same day, with preparation named as the step that made speed safe.
- Beginner summaries note the can's bead control as easier than expected, once the trigger pressure is learned on a practice surface.
- The watch-out repeated by owners is the same discipline as tube RTV: a rushed bead is a leaking bead, however fast the product cures.
Permatex The Right Stuff: who should not buy
Do not buy The Right Stuff as a first sealant, or as a shortcut past surface preparation. Speed rewards a beginner who already controls a bead; it punishes one who does not, and it never replaces a gasket the manual specifies.
Permatex The Right Stuff: pair it with
Pair it with the Permatex Ultra Black, which keeps the setup tidy and repeatable.
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Keep the can upright and capped between uses, and practise the trigger on cardboard first. our synthetic rope maintenance guide
Best for fasteners: Permatex Threadlocker Blue
Best for Fasteners
Why the Permatex Threadlocker Blue is our pick
Threadlocker Blue is our fastener pick because beginners confuse two different sealing jobs: flanges need RTV, threads need threadlocker. Permatex's medium-strength blue formula is an anaerobic threadlocker for nut and bolt applications from one quarter inch to three quarters of an inch, or 6 to 20 millimetres, that prevents loosening and corrosion while remaining removable with hand tools. That removability is the whole point: a fastener that must come apart for service must not be glued shut.
Permatex Threadlocker Blue key specs
- Part number: Permatex 24200 (6 ml tube in this guide)
- Type: anaerobic threadlocker, medium strength
- Colour: blue
- Fastener range: 1/4 in to 3/4 in (6 mm to 20 mm)
- Removability: removable with hand tools
- Functions: prevents loosening and corrosion
- Form in this guide: liquid, 6 ml tube
- Companion sizes: gel and larger tubes exist under the same formula
- Not a gasket maker: do not use on flanges
- Not for: fasteners that must never move (use a high-strength formula, with care)
- Maker: Permatex (ITW)
- Warranty: Not published in the sources checked for this guide
Permatex Threadlocker Blue: fits and best for
Best for bolts and nuts on brackets, covers, accessories and winch mounts that vibrate loose but must be removable for service. It fits every vehicle owner, because a winch mount, a bumper bracket or a battery hold-down that loosens under vibration is a safety problem, not a nuisance.
Permatex Threadlocker Blue pros and watch-outs
- Stops vibration loosening without permanent bonding
- Removable with hand tools, so service stays possible
- Prevents corrosion on the thread, easing future removal
- Small tube suits occasional use without waste
- Clear strength class: medium means serviceable
- Not a flange sealant; using it on a gasket joint fails
- Needs clean threads and cure time to work
- Wrong strength class, high or low, creates a future problem
- Small tube runs out on a big job; size the tube to the job
Permatex Threadlocker Blue: what owners report
- Owner themes on the listing stress the serviceability: bolts that stayed put through vibration yet broke free cleanly at the next service.
- Beginner summaries repeatedly mention the same mistake avoided: medium blue where red high-strength would have made the next job miserable.
- The watch-out is thread cleanliness: owners who applied it over oil or rust report weak hold, which is a preparation failure, not a product failure.
Permatex Threadlocker Blue: who should not buy
Do not buy Threadlocker Blue for a flange, a gasket joint, or a fastener that must never be removed. It is a thread product with a thread job; flange sealing belongs to the RTV tubes in this guide, and permanent fasteners belong to a different strength class chosen deliberately.
Permatex Threadlocker Blue: pair it with
Pair it with the Permatex Ultra Black, which keeps the setup tidy and repeatable.
We may earn a commission at no cost to you.
Apply threadlocker to clean threads only, and let it cure before loading the fastener. our recovery kit guide
Spec comparison
| Spec | Ultra Black | Ultra Grey | Ultra Copper | Right Stuff | Threadlocker Blue |
|---|---|---|---|---|---|
| Type | RTV, oil-resistant | RTV, rigid | RTV, max temp | Instant gasket | Threadlocker |
| Part number | 82180 | 82194 | 81878 | 85224 | 24200 |
| Form | 3.35 oz tube | 3.5 oz tube | 3 oz tube | 7.5 oz can | 6 ml tube |
| Temperature | To 400 F cont. | High torque | Maximum temp | Fast return | Thread range |
| Sensor safe | Yes | Yes | RTV family | Not applicable | Not applicable |
| Tack-free | 2 hours | 1 hour | Per tube | Fast | Per tube |
| Full cure | 24 hours | Per tube | Per tube | Fast | Per tube |
| Head gasket? | No | No | No | No | No |
| Best job | Oil joints | Torque joints | Hot joints | Same-day jobs | Vibrating bolts |
| Check Price | Ultra Black | Ultra Grey | Ultra Copper | Right Stuff | Threadlocker Blue |
|---|---|---|---|---|---|
| Button |
Scores below are editorial judgement from the maker figures and owner themes in this guide, not test results.
| Pick | Editorial score |
|---|---|
| Permatex Ultra Black | 9 |
| Permatex Ultra Grey | 8 |
| Permatex Ultra Copper | 8 |
| Permatex The Right Stuff | 8 |
| Permatex Threadlocker Blue | 8 |
Installation basics: the bead that seals
Preparation decides the result. Remove every trace of old sealant with a plastic scraper and a suitable remover, taking care not to gouge aluminium faces, then clean and dry both faces completely. Cut the nozzle to the bead size the job needs, usually about one eighth of an inch for most joints, and lay one continuous bead, tracing the internal shape of the joint and every bolt hole, exactly as the Permatex directions describe. Assemble promptly, torque the fasteners in sequence to the manual specification, and do not disturb the joint during cure. For winch vehicles, the same discipline applies to differential and transmission covers opened during servicing, as described in our winch maintenance checklist and our winch motor repair guide.
Cure time is part of the job, not an afterthought. Ultra Black needs 24 hours for a full cure, Ultra Grey tacks in about an hour, and The Right Stuff is built for fast return, but every product needs its own cure respected before oil, coolant or load returns. Clean excess sealant from the outside only, never push it into the joint, and keep uncured sealant out of oil passages by keeping the bead thin. If a joint weeps after a careful job, the cause is usually preparation or a warped face, not the tube, and re-doing the preparation is the fix.
Safety essentials
- Work in a ventilated area; RTV and threadlocker vapours are not for closed garages.
- Wear gloves and eye protection; uncured sealant on skin or in eyes needs prompt washing.
- Keep sealants away from sparks, flames and hot surfaces until cured.
- Never use a sealant on a cylinder head gasket joint or where the manual specifies a gasket.
- Keep threadlocker off painted surfaces and plastics it is not rated for.
- Store cans and tubes capped, upright, cool and out of children's reach.
Three accessory picks from this guide's verified pool, for cleaner and safer sealing work:
Permatex Ultra Black as the default tube:
Permatex Ultra Grey for high-torque joints:
Permatex Threadlocker Blue for fasteners:
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
| Joint weeps after sealing | Old sealant or oil left on the faces | Strip fully, clean, dry and re-seal |
| Sealant squeezed into oil passages | Bead too thick | Use a thin bead; inspect passages before assembly |
| Joint leaks at bolt holes | Holes not traced with the bead | Trace every hole; torque in sequence |
| Sealant fails from heat | Wrong temperature product chosen | Match the product to the joint temperature |
| Threadlocker holds weakly | Oily or rusty threads | Clean threads fully; allow cure time |
| Fastener will not come apart | Wrong strength class used | Use medium blue for serviceable fasteners; follow the manual |
Who should NOT buy these
Anyone sealing a head gasket should not buy any RTV in this guide. No RTV here qualifies as a head gasket or head gasket sealant, and Permatex says so explicitly. Buy the correct head gasket and follow its procedure.
Beginners on their first-ever sealing job should not start with The Right Stuff. Its speed rewards bead control already learned on a tube; it punishes a first bead. Learn on Ultra Black, then add speed.
Owners of gasoline-contact parts should not buy Ultra Grey. Its technical data sheet excludes gasoline contact, and that exclusion is a hard limit, not a preference.
Anyone sealing a flange should not buy Threadlocker Blue for that joint. It is a thread product; flanges need RTV, and the two jobs do not substitute.
Anyone who will not wait for cure should not open a joint at all. A rushed cure creates the leak the sealant was bought to stop. Schedule the cure first, or choose The Right Stuff deliberately.
Final verdict
Best overall: Permatex Ultra Black — Check Price
Best for high-torque joints: Permatex Ultra Grey — Check Price
Best for high heat: Permatex Ultra Copper — Check Price
Best for fast return to service: Permatex The Right Stuff — Check Price
Best for fasteners: Permatex Threadlocker Blue — Check Price
FAQ
What sealant should a beginner buy first?
Permatex Ultra Black. It covers oil pans, valve covers, transmission pans, timing covers and differential covers, it is oil-resistant, sensor-safe and flexible, and its method teaches every RTV skill a beginner needs. Add specialists only after the first successful job.
Can I use RTV instead of a gasket?
Only where the maker allows a formed-in-place gasket. If the manual specifies a pre-cut gasket, use that gasket, with RTV only as a dressing where the manual allows it. RTV never replaces a head gasket, and this guide's products all carry that exclusion.
How long must RTV cure before I drive?
Ultra Black needs 24 hours for a full cure, with 2 hours to tack-free, and Ultra Grey tacks in about an hour. The Right Stuff is built for fast return to service. Never refill oil or load the joint before its cure finishes, because early loading is the most common beginner cause of a repeat leak.
What is the difference between Ultra Black and Ultra Grey?
Ultra Black is flexible and oil-resistant, for oil-exposed joints. Ultra Grey is rigid and high-torque, for vibration-heavy and import assemblies. The choice is the joint's movement and the manual's specification, not personal colour preference.
Can sealant fix a leaking head gasket?
No. No RTV in this guide is a head gasket sealant, and Permatex states the exclusion explicitly. A leaking head gasket needs proper diagnosis and a head gasket repair, not a tube of sealant.
How thick should the bead be?
Thin and continuous, usually about one eighth of an inch for most joints, tracing the joint shape and every bolt hole. A thick bead squeezes into oil passages and creates new problems, while a broken bead leaks at the gap. Practise on cardboard first.
Do I need to remove all the old sealant?
Yes, completely. Old sealant left on the faces is the most common cause of a second leak, because the new sealant bonds to the old material instead of the metal. Use a plastic scraper to avoid gouging aluminium, then clean and dry the faces.
Is Threadlocker Blue the same as a sealant?
No. Threadlocker Blue locks threads against vibration and corrosion, and it is removable with hand tools. It does not seal flanges, and RTV does not lock threads. Beginners who name the joint first, flange or thread, never confuse the two.
Which sealant for a turbo or exhaust joint?
Permatex Ultra Copper, the maximum-temperature RTV in this guide, designed for turbocharger and exhaust-adjacent applications. Confirm the application on the tube, respect its cure, and remember that where a gasket is specified, a gasket is still required.
Sources & changelog
- Permatex Ultra Black listing record (ASIN B0002UEN1U)
- Permatex Ultra Black technical data sheet
- Permatex Ultra Grey listing record (ASIN B000HBGI8K)
- Permatex Ultra Grey technical data sheet (PDF)
- Permatex Ultra Copper listing record (ASIN B0002UEOPA)
- Permatex The Right Stuff listing record (ASIN B000HBM4MO)
- Permatex Threadlocker Blue listing record (ASIN B0002UEMZ2)
- Permatex Ultra Black directions for use
- Permatex Ultra Blue retailer page (context only; not a pick, ASIN unverified)
- Permatex Ultra Grey small tube listing record (ASIN B004WJPMHQ)
Changelog — October 30, 2026: guide first published.
By Leo, Founder, WinchInsider
Leo covers winches, recovery gear and the vehicle electrical and maintenance kit that supports them, working from maker documents and owner reports rather than bench claims.
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