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To Anti Seize or not to Anti Seize

Not quite as popular of an internet debate as "Which Oil to Use" or "Which Wax to Use" is the question of to "Use Anti Seize" on your spark plugs or NOT.

If you look long enough you can find the answer YOU want. And if you search hard enough you can probably find the same manufacture, auto or spark plug, saying yes to "Use Anti Seize" and "Not to Use Anti Seize".

So lets look at the reasons to use Anti Seize

  • It "Stops electrolytic corrosion between steel plugs and aluminum heads", that can keep you from removing your plugs one day.

Well that does sound pretty important.

Ok what about the reasons NOT to use Anti Seize?

  1. Anti-seize causes you to over torque the spark plugs, even when you use a proper torque wrench.
  2. There is no need to use anti-seize on your plugs. If you don't over tighten the spark plugs.
  3. Using Anti Seize will change the heat range of your spark plugs
  4. Spark plugs with special metal plating do not require anti-seize
  5. Anti Seize will ruin your spark plug insulator
  6. Anti seize will get hard and you cannot get the plugs out
  7. Anti seize will get hard and fall into your cylinder when removing the plug and screw up your engine
  8. Anti Seize will screw up your O2 Sensors

I am sure there are more but these were the common ones I ran across.
If true those all seem pretty important reasons why not to use Anti Seize.

Let's go through each of the reasons.

1. Anti-seize causes you to over torque the spark plugs.
YES this can be true, IF you put Anti Seize all over the threads and the conical shoulder, (I believe this would be the same for the surface area of a crimp washer also).

Anti Seize compound is a lubricant and COULD allow you to over torque your spark plugs. NOT GOOD.

But there are a couple of ways to get around this. Old timers will remember when Spark Plug manufactures would not give a torque specification but instead would give you a torque angle to turn the plug past "finger tight". For example for this plug the angle is 1/16th of a TURN once the plug is finger tight.
This torque angle is valid with or without a lubricant on the threads. That is why many assembly instructions use a torque angle specification.

Below is an inexpensive torque angle gauge that is available at most automotive stores for around $10.

Ok so if you want to use anti size you can get around the over torque concern by using a "Torque Angle Gauge".
Note: I have used the torque wrench in combination with the angle gauge and even using Anti Seize on the threads only, the recommend foot pounds and the 1/16th angle were the same.

2. There is no need to use anti-seize on your plugs. If you don't over tighten the spark plugs.
OK, well who means to "over tighten" their plugs? Ok, we all agree, "Don't over tighten your plugs".

3. Using Anti Seize will change the heat range of your spark plugs.
OK, my thinking here is if you could change the heat range of your Super Dooper $10 plug with 10 cents of Anti Seize compound then there would be SOMEBODY out there selling "Spark Plug Heat Range Adjustment Compound". I haven't seen any out there. Also my own tests of smearing Anti Seize on the side of a large glass filled with boiling water and comparing the temperature of the Anti Seize side and the non Anti Seize side using an infrared thermometer showed no difference. Seemed to me that the Anti Seize compound was a poor insulator.

4. Spark plugs with special metal plating do not require anti-seize
OK, if your plug is coated with a special coating maybe you don't need the Anti Seize compound.

5. Anti Seize will ruin your spark plugs insulator
OK this is pretty easy, DO NOT get any Anti Seize on the insulator.

6. Anti seize will get hard and you cannot get the plugs out
Well it is true that sometimes the Anti Seize does seem to get hard but I don't think it gets hard enough to keep that plug from moving. I haven't heard of anybody using Anti Seize as glue lately.

7. Anti seize will get hard and fall into your cylinder when removing them and screw up your engine
A thin coat of Anti Seize gets really thin as you thread the plug in. An ultra thin coat will travel up the threads and onto the smooth side of the plug located between the threads and the conical shoulder. I have had this area lightly covered but it never showed signs of flaking off. Also it was never enough to travel up to the shoulder either. This might be a good time to mention that when using the full threaded plugs in the half threaded head, I only put a thin coat of Anti Seize on the first 6 threads.
I can not discount this concern but I have never seen anything that would lead me to believe that dried Anti Seize compound is flaking off and falling back into the spark plug hole.

8. Anti Seize will screw up your O2 Sensors
They do make Anti Seize compound that says it is safe for O2 sensors and other sensors so I guess if you used the wrong Anti Seize compound it could do harm. So if you do use Anti Seize, use the O2 sensor safe Anti Seize compound.

Ok, so there you have the negatives and the positive. NOW if you are going to use an Anti Seize compound you have to choose which one.

I am going to go over some of the different types of Anti-Seize. I know there are more but for the automotive projects I am seeing basically three kinds that are applicable.

To make things simple I am going to use the Permatex line. Loctite has a few more selections but they have pretty specific uses. I don't think you will need "Food Grade" for your Mustang.

1. Permatex® Anti-Seize Lubricant

A highly refined blend of aluminum, copper and graphite lubricants. Use during assembly to prevent galling, corrosion and seizing and to assure easier disassembly. Temperature range: -60°F to 1600°F (-51°Cto 871°C). Salt, corrosion and moisture resistant - ideal for marine use. Non-aerosol version meets Mil Spec #907E. Aerosol - Level 3*

2. Permatex® Copper Anti-Seize Lubricant

A premium quality copper anti-seize and thread lubricant that may be used to prevent seizing, corrosion and galling where high temperature conditions exist. Contains a high percentage of micro-fine copper flakes in a semi-synthetic grease carrier and is fortified with high quality rust and corrosion inhibitors. Temperature range: -30°F to 1800°F (-34°C to 982°C). Provides good electrical conductivity. Meets Mil Spec #907E.

Suggested Applications: Spark plug threads installed in aluminum, exhaust manifold bolts, engine bolts, oxygen sensors, knock sensors, thermostat housing bolts, fuel filter fittings, and battery cable connections

3. Permatex® Nickel Anti-Seize Lubricant

Protects metal parts from seizing and galling at temperatures up to 2400°F (1316°C). Copper-free, use under conditions of extreme pressure and temperature, and with stainless steel, titanium and nickel alloys.

Suggested Applications: Exhaust manifold bolts, exhaust system bolts, muffler clamps and tailpipe assemblies

Ok for me, having had a spark plug break off in a head before,

  • I always use a very thin coat of Anti Seize on the spark plug threads.
    Note: For the heads on the Bullitt, I only apply the Anti Seize to the first six threads of the plug
  • I make sure not to get any Anti Seize compound on the center electrode.
  • The first couple of times I tightened the plugs I used both a breaking torque wrench and the angle torque gauge to make sure the torque did not exceed the angle.
  • I used to just use the Nickel Anti Seize but after writing this page I will use the Copper Anti Seize from now on. I never had a problem with the Nickel Anti Seize but clearly the Copper is what I will be using the next time I change plugs.
  • Ford says the plugs should be torqued to 11 foot pounds. The plug manufacures I looked up showed the torque to be 7.2 to 14.5 pounds for our plugs. I normally use 13 foot pounds.

Click here to view a PDF by "NGK" where they mention not to use Anti Seize.
They use a LOT more Anti Seize than I would

Click here to view a PDF by "Autolite" where they say to use Anti Seize.

Here is a screen capture I found on the Motorcraft website last year before they changed everything around. I am unable to find this "Tip" on their website.

And just so we are perfectly clear, the image below is from a 2004 Motorcraft Spark plug guide and it states,

"The use of thread lubricants is not recommended but if lubricant isused, torque values should be reduced to avoid possibility of over torquing."

Ok for you? Your choice.

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