Spark plugs and anti-seize

[Steve Wood]

I have read this in the past but someone sent it to me this morning in case I had not seen in.

http://www.ngksparkplugs.com/pdf/TB-0630111antisieze.pdf

Normally, I do not ever use antiseize on plugs because I figure I will change them long before they weld themselves to the head and the stuff is so damn messy, but...I know some gob it on everything so be aware

[earlbrown]

It's interesting how they only showed a 10mm plug which has a HUGE reach.  Back in my motorcycle days I used many many 10mm plugs and used antisieze on all of them. Granted I use a smear coat not a glob.   When 'hand torquing' the feel I used was to collapse the gasket while thinking about stripping the treads.   It never dawned on me that I could rip the plug in two with aluminum as the head material.


Before I read it, I was thinking this was the story about the GM 3.1 (or something similar) that had the running condition due to globs of antiseize on the plugs.

[motorhead]

I just did NGK plugs in both the Camaro and TBSS (LS1 (TR5) and 2 (TR6), respectively) and still put a dab of copper anti-seize on the threads.

I think it is important to note that it is on "initial" installation that the coated plugs don't require a lubricant to avoid sticking in the head; but once that coating is broken you are going to want to consider it regardless of your stance on the issue.

I also think that tapered seat plugs will be less suspect of stretching and breaking.

[Steve Wood]

I thought anti seize was to prevent electrolysis between iron and aluminum?  Nickle plating on the plug threads would accomplish the same as nickle antiseize and zinc would do the same as the cheaper antiseize, would it not?

[Pyro6]

I talked to a Champion rep at one our NAPA conventions. He claimed that all their plugs were made with a coating to eliminate any seizing issue, I forget what the coating consisted of. Good points made already, change them soon enough and it won't matter. During testing and such it can't hurt to put a small dab on the threads and the tapered portion.

[bryes]

I'd be willing to bet that this failure is more of an issue of over-tightening the plugs rather than the lubricant used.  How can NKG say that never seize would lead to twisted plugs, then recommend using never seize on "plugs that don't have metal shape plating"??  Are we to believe that the combination of "Zinc chromate metal shape plating" and never seize reduces friction to the point that the plugs start twisting off under normal preloads; while at the same time using never seize or "metal shape plating" by itself does not??

Maybe I read the article wrong, but the clamping forces generated from torquing bolts (or in this case plugs) do not become infinite even if friction is completely absent. Because friction between two lubricated steel surfaces (threads) can be pretty low and friction itself is unpredictable, a properly designed plug should be able to withstand the recommended preload regardless of lubricant. 

[Steve Wood]

the type of lubricant used has a lot to do with the clamping force or "tightness" in this case.

Consider the difference in clamping force applied by a head bolt when oil is used as a lubricant, or another substance as per ARP's examples.  In this case, we are dealing with radial torque on the plug housing which will be higher if anti seize is used in comparison to one that has nothing added and both are torqued to the same level.

[earlbrown]

the only thing that gets me is thinking about torquing to failure.  Granted I get that using antiseeze as a lube will generate more thread loading for the same amount of radial torque....

That being said I would imagine that if I were to take 100 10mm plugs in alum heads and torque them all until failure...   I would end up with a bunch of stripped out heads.   When the plug is bottomed out and torque is still applied, you have steel threads trying to shear off alum heads.  Then Newton was eating an apple and said that at the same time the aluminum treads are trying to rip a steel plug in two.

My money is on the steel.

[Steve Wood]

change them often enough and there is no reason to put anything on them whether they are coated or not.  The secret is to snug them down and not use King Kong for your labor unless you give him a good torque wrench.  I can see using some anti seize on an uncoated threads that are not destined to be removed for 100,000 miles, but, on a hot rod that gets changed frequently.  You have to work pretty hard to find a plug cheap enough that has uncoated threads that is made for a modern 100,000 mile plug interval car or truck anyway.

Earl, I agree, torquing them to spec with anti seize on them is most likely going to damage the aluminum threads on the head side before hurting the plug.

These discussions always make me laugh when I see people belittling engineers that work for car and oil companies.  I bet this stuff would be a lot cheaper if they would just wise up and fire all those idiots

[tb3]

I've never regretted putting a tiny dab of C5 on any of my plugs.
But it probably is a waste of time.
love using it on my brake parts though

[bryes]

I think that if the plugs were solid steel, then the AL head's  threads would be most likely fail before anything else. But the plug is hollow so it failed across its cross-section where the wall is thin. So in this case the AL threads are not the weakest link, and would probably not usually fail first.

This type of failure shown in NGK's pictures will  happen if the plugs are over-torqued. I should know, I just recently failed 2 or 3 that way trying to remove them after they were seized! Other than the rust, you'd have a hard time telling the difference between mine and those in the article. And mine darn well for sure weren't  because the lube was too slipery!

As for Engineers, I try to listen to them (not that we know an engineer wrote this), but this article just spit in the face of common sense to me.  In essence it says that,


1: Zinc coat = good
2: Never seize = good
3: Never seize + zinc coat = failure

Are we supposed to believe that zinc coat + never-seize forms some sort of super lubricant?
If so then maybe we should patent this and sell it to ARP!

[Steve Wood]

I guess perception is more important that reality.  It made perfect sense to me

[motorhead]

I guess perception is more important that reality.  It made perfect sense to me

I think a liberal coating of common sense is what this issue really requires.

[bryes]

Well Steve, you're among the most knowledgeable buick guys out there, at least in my estimation, so I'll never blame you for going with your gut. Plus, like you have said, its not like you have anything to lose by following their advice or anything to gain ignoring it!  I just need to make sure that you ain't fixin' to add a dollop of  "the gray stuff" for your next oil change to eliminate friction on your cam lobes

For me, I'd have to see more evidence (and warnings on the back of never-seize cans) before I'd be afraid of using it on my spark plugs, coated or not!

[Steve Wood]

In the '50's we added a dollop of Comet to the oil to break in chrome rings...we were smarter than the ring company engineers in those days too!