<VV> anti seize on plugs

[Sethracer at aol.com]

_djtcz at comcast.net_ (mailto:djtcz at comcast.net)   writes:

Hi  Clark, 

I 'd bet a dollar menu cheeseburger the heat transfer is as  good or maybe 
little better with antiseize or grease. I anticipate No problem  with the 
electrical contact needed as a ground connection either. 
Because Clark wrote:
I have just done an internet search on this topic and nowhere did I find  
any
info that you shouldn't use it on spark plugs. So, apparently I am  wrong!!!
This is heart breaking as I have never been wrong before!  GRIN
Clark Hartzel
 
Good News Clark - You were right - Maybe.
 
Well - You pay your money and you take your choice.
 
Here is my take:
1- Clean dry threads both on plug and head
2- Published Torque value used only when dry.
3- If you add anti-seize, watch/read plug temp/heat range. May insulate and 
 plug will run hot. Adjust torque values during installation.(downward)
4- I use thread inserts on all my spark plug holes, so all bets are off  
anyway! - Seth 
 
But in case anybody cares:
 
 - Advice from the plug guys
 
 
Autolite
We do not recommend the use of any anti  seize products for installing 
spark  plugs. Anti-seize compounds are typically composed of metallic,  
electrically conductive ingredients. If anti seize compounds come in contact  with 
the core nose of the plugs, it can lead to a misfire condition. Anti seize  
compounds can also have a torque multiplying effect when installing plugs. 
This  can lead to thread distortion and thread galling resulting in cylinder 
head  damage. Autolite spark plugs are  nickel plated to resist the effects 
of corrosion and seizing. However, plug  seizure is aggravated further when 
steel plugs are installed into aluminum  cylinder heads for a long period of 
time. 

AC/Delco
Do not use any type of anti-seize compound on  spark plug threads. Doing 
this will  decrease the amount of friction between the threads. The result of 
the lowered  friction is that when the spark plug is  torqued to the proper 
specification, the spark  plug is turned too far into the cylinder  head. 
This increases the likelihood of pulling or stripping the threads  in the 
cylinder head. Over-tightening of  a spark plug can cause stretching of the  
spark plug shell and could allow blowby  to pass through the gasket seal 
between the shell and insulator. Over-tightening  also results in extremely 
difficult removal. 

Champion 
The  following material is excerpted from the Champion Spark Plug  Handbook.
Champion spark plug  shells (the threaded part) use an extruded steel to 
maintain exact tolerances.  The extruded shell goes through a cold rolling 
process to form the threads. This  prevents sharp edges which could cut new 
threads into aluminum cylinder heads. Once  the shell is formed and threaded, 
it is zinc-plated to extend its life and  reduce the chances of seizure in 
aluminum cylinder heads. Our  latest technology combines Tin Tac" and 
ULTRASEAL'M coatings over the plating to  further reduce corrosion and seizure. 
Champion recommends that you do not use an  anti-seize compound, since one has 
already been applied to the plugs at the  factory.

Intrigued, I went a-googling for any information I could  find from NGK on 
this topic. I found this excellent Canadian  website that lists the complete 
set of NGK Technical Bulletins. According to the  Bulletin, NGK states that 
all their plugs are manufactured with a special metal  shell (trivalent) 
plating to prevent damage to the cylinder head. For  plugs with this special 
metal plating, anti-seize is not recommended during  installation. Applying 
anti-seize to these plugs will cause the installer to  mistakenly over-torque 
the plug in the cylinder  head stretching the metal between the last thread 
and the seal between  the cylinder head and plug. This  increases the 
probability that the spark plug will  either break during installation or upon 
removal.

For plugs without a  special metal shell plating, NGK advises the use of 
anti-seize and provides  photos of unplated plugs installed without anti-seize 
where the steel threads  have bonded with the aluminum in the cylinder head 
 requiring replacement or repair of the head. 

Denso also  warns against the use of anti-seize in their Spark Plug 
Installation instructions:
"If a  thread lubricant such as grease is coated on the thread, tightening 
to the  recommended torque is tightening too much; this has been linked to 
seal leakage.  Do not use a thread lubricant."