[FJtest]

No, you should never use anti-seize on spark plugs! Heres why:

• It acts as an insulator affecting the total electrical conductivity of the spark plug. This is the opposite of the desired purpose of a spark plug

Absolutely untrue, and can be easily proven by making some simple measurements with an ohmmeter or even a milliohmmeter if you are interested in looking for hundredths of an ohm.

Just for the sake of argument, let's say that the anti-seize introduced 0.1 ohm of resistance, or 1.0 ohms, or even 10 ohms of resistance in the secondary (spark) circuit. Given that the plugs used in almost all modern IC automotive engines have internal resistor value of around 5,000 ohms, do you think that a resistance of 5,000.1 ohms will make any detectable difference in engine operation, or spark energy, compared to a resistance of 5,000 ohms?

How about 5,001 Ohms, or 5,010 Ohms?

And remember that the a plug's resistance tolerance is typically +/- 10% or greater, so a brand new plug can have a resistance of anywhere between 4K and 6K ohms.

 

[FJtest]

So I gather that you reduce the factory shop manual recommended spark plug torque setting by that ~15% amount then when using any version of anti-seize?

Yes.

The reduction in thread friction is very similar regardless of the specific type of anti-seize used, so general reduction in applied torque is commonly recommended. The 3/4" reach plugs used in the 1GR-FE engine provide a lot of thread shear area, so the reduction in tightening torque probably isn't as critical as it is in aluminum-head engines using shorter reach plugs.

Anti-seize manufacturers don't typically provide any specific recommendations on fastener tightening torque, as they have no idea what your application is, what materials are involved, etc.

 

[mk3]

On aluminum heads? Nope. Antisieze or any pipe dope increases the chance you'll overtighten it.

 

[FJtest]

On aluminum heads? Nope. Antisieze or any pipe dope increases the chance you'll overtighten it.

Uhhh ... that's why why you reduce the installation torque by 15%, so despite the reduction in thread friction, you end up with the same tensile load in the threads.

 

[robfowler54]

Do you use anti-seize on your spark plugs?

Love to hear about why or why not and the different theories out there.

Also let me know what plugs you use (OEM? Iridium?) and what brand anti-seize do you use (if you use it)

Absolutely! As a professional Mechanical Engineer anti sieze is an amazing addition to spark plug threads and seat. Most guys have no idea what it is and have never used it on anything. Its a lifesaver for mechanics when used anywhere moisture or corrosion might occur. It will prevent stripped threads and make most mechanical assemblies go together and come apart years later very easy if used properly. Use it!!

 

[FJ Mike]

All the reasons not to use compound are either because they are improperly used or the wrong ones. After having to put heli-coils where spark plug threads used to be in my '63 VW, I used compound in many plugs (aluminum heads only) ever since over the years, with absolutely no ill effects. Of course, it's not essential, but cheap and easy insurance. I've done three sets of plugs this way on my fj and it runs like new.

 

[Alpine_FJ]

Always do.
All the vehicles I've had since the 1978 JMC Jimmy I owned have had aluminum heads. If you've ever felt the joy of having the threads come out with a plug you know why I always use anti-seize on them. Since I started using it about four decades ago I've never had a problem.

 

[mikey]

There are various types of anti-seize available. If you are going to use anti-seize make sure you are using the correct one.

Right tool for the right job.

 

[Nameuser]

There are various types of anti-seize available. If you are going to use anti-seize make sure you are using the correct one.

Right tool for the right job.

Yeah, never thought there would be a right or wrong anti-seize for plugs but, thankfully I always bought the little Permatex sparkplug "ketchup" size type packets.

 

[City fighter]

Do you use anti-seize on your spark plugs?

Love to hear about why or why not and the different theories out there.

Also let me know what plugs you use (OEM? Iridium?) and what brand anti-seize do you use (if you use it)

Never on aluminum heads.Cast different story.See cast problems .

 

[norm356]

"Never on aluminum heads.Cast different story." - actually its the opposite: aluminum threads are much more likely to gall, stick and tear during assembly and disassembly of threaded joints. Same as stainless steel and magnesium: these non-ferrous metals develop a microscopic layer of oxide on the surface which protects them from further corrosion but it also creates a great deal of friction while torquing threads, machining and so on. Way more than steel or CI. So, while machining those metals special cutting fluids must be used to prevent tearing of the material and thread coatings use to prevent damage while torquing. This is why modern spark plugs come with a treatment on their threads.

Cast iron, on the other hand, is much easier to work with (machine it and thread into it).

Regarding likelihood of one or the other to be over-torqued by a careless mechanic, a softer material like aluminum the number of threads is increased accordingly, so the torque applied is not decided based on how soft the material is but on how tightly the threaded joint must be held to do its job.
(note how many spark plug threads in an aluminum cylinder head compared with the very few in a CI head, they do the same work).

Norm

 

[Kaiju]

Uhhh ... that's why why you reduce the installation torque by 15%, so despite the reduction in thread fiction, you end up with the same tensile load in the threads.

Just confirming.

 

[FJtest]

Yeah, never thought there would be a right or wrong anti-seize for plugs but, thankfully I always bought the little Permatex sparkplug "ketchup" size type packets.

Actually, just about 'any' anti-seize lubricant will work just fine for spark plugs, skid-plate bolts, slider bolts, etc. because the temperatures and environmental conditions are so mild.

It's when you get into the 'exotic' environments (temps above 800F, high vacuum conditions, aerospace applications, exposure to nuclear radiation, etc.) where the unique features of specific types of anti-seize become important.

 

[JAFFJ]

Never any joy when water soaked and rusted plug threads come out with the plug. *Plug gaskets don't seal as well as you think.
Another disadvantage to neverseize is the oil in it dries out. Then you put another coating on the next plug thread. Eventually it can build up and do the opposite of what it was intended for.

A third disadvantage is good old galvanic action. Antiseize/Neverseize whatever you want to call it is typically compounded from aluminum, copper and zinc. Add in a different alloy of the aluminum head and toss in the steel sparkplug and you get the picture.

Yeah I use it. The nickel content one not the metal cocktail one.