I'd be very very surprised if anyone can honestly say they can detect the difference between 2 thou, 10 thou or even 25 thou make to a plug's firing. This is kinda like an oil thread....not that there is anything wrong with that.

 

Gapped a tad narrow should give longer useful life. +/- .004" (0.1 mm) isn't much variation compared to the increased gap of a worn out sparkplug.

 

AutoLite makes Motorcraft spark plugs for Ford. Can't be all that bad What vehicle manufacturers use NGK for OE plugs?

Lack of warranty serves two purposes
1. Increases sales maybe, helps keep the price down a little, more revenue / money for the higher ups.
2. No after sales commitments

 

I guess the Autolite branded ones are the ones that fall on the floor before they leave the plant. Motorcraft branded plugs are fine. Even Fords don't like Autolites.

Dodge uses NGK plugs for certain applications. Ever notice your service manual gives you a Champion and a NGK part number? And as Pete said, for Japanese cars you are guaranteed to find Denso or NGK in them from the factory. Even BMW has ditched Bosch for NGK. The "ultimate driving machine" (😆😂🤣) decided that German engineering wasn't good enough.

 

Warranty would be nice, but a quality product that doesn't need a warranty within its normal service life is better. I think Autolite did the lifetime warranty to try to counter their reputation. Customers that insisted on Autolites always came back in under a year, usually under half.

 

I usually do a quick check on spark plugs to see if anything has happened to change the gap. I dropped one way back when. Should have heard that flat 4 backfire. Cant say that I have ever adjusted a double platinum or Iridium spark plug out of the box. They were pretty much dead on accurate. Minor adjustments just make things worse. If a tad tight, don't worry.

I doubt they are gapped by humans when packaged, all done precisely by machines with no arthritis.

 

I have always gapped my own plugs. I don’t trust the pre gapped malarkey. I even had a parts counter dude offer to gap plugs for me, I told him don’t bother because I will do it before installing the plugs. He said it was no trouble, unboxed the plugs ran them across a coin gauge, boxed them up and said “have a nice day”. Yeah right.

Out of six plugs only two were the same measurement, one plug was at spec, the rest were .002” to .003” off. I will say they were all in the spec range but I like my plugs gapped at the low side, so I regapped all of them with pin gauges.

In the situation where you do not have the correct size gauge but have one higher and one lower just use what you have. Gap the plug so that the big gauge won’t pass and the small one just has no drag when passed. This will get you as close as possible.

Eric


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Be careful of coin-gappers. I got one off Amazon and the indicated measurements were significantly off when I measured with calipers.

 

Coin type gapper is fine. Just don't wedge the electrode with it. Use the hole to do it as intended. I either use that or feeler gauges and needle nose pliers. Every one of the gauged wire types I've used has fallen apart and rarely has the size needed.

Those wonky out the box gaps are exactly why you should check pregapped plugs.

 

All plugs should be gapped, even the ones that claim to be pregapped. Champion is OEM, but many of us prefer NGK. Jeepman likes pointing out their short warranty period, but I've never seen one fail early so it's a bit irrelevant.

 

Why they made the decision to trash their reasonably good warranty isn't irrelevant. Did they explain why to their Customers? They need to know that information and backing product matters. Compare their warranty to any other spark plug manufacturer. NGK gets a D-.

Ajax Storm Doors has a better warranty than that. Just sayin.

No failures you say? From Post #8

In Our Experience
For NGK warranty purposes, we have to ship all damaged spark plugs back to NGK UK so that they can be officially examined and documented. As of now, it turns out 100% of the spark plugs in the last 5 years that were returned due to thread breakage were the result of customers using thread compound, or simply over tightening them. The NGK warranty reports are always compiled with detailed photographs pinpointing the exact reasons for failure, even to the very smallest of details such as hex swelling and magnified photos are taken and recorded.

 

Jumping back into the thread with a spark plug related question. The OEM plugs are Champions but they’re 0.044” instead of 0.043”. Does that mean they the have to be gapped first? Safer bet is to go with OEM aka Mopar?

 

Looking at rockauto.com, the OE gap is stated differently per plug
Champion 9407: 0.041 vs 0.043 OE
NGK: 0.044 vs 0.044 OE
AutoLite: 0.040 (1 mm) same as what the Haynes Manual says vs 0.040 OE.
Denso: 0.035 (whoa) vs ? OE
Bosch: 0.040 (1 mm) same as what the Haynes Manual says vs ? OE
PartAvatar.ca says 0.044 as OE for Champion 9407
They can't make up their minds as to what the OE specs are.

Per rockauto.com the Champion 9407 spark plug is gapped at 0.041 with this stipulation:

This spark plug is pre-gapped, but may require minor adjustments with a Spark Plug Gap Tool / Feeler Gauge to match your engine's specifications. For proper engine performance, gaps should be within ±0.004" of OE-Recommended value.

Not to worry, a little closer gap means the spark plug will maintain its closeness to OE gap longer.

 

I have gone through the nightmare of broken spark plugs because they were rusted into the heads. I HIGHLY recommend using anti-seize compound.....

 

Steel spark plugs in aluminum heads?

Over torquing can cause that.

The "trivalent plating" is an anti-seize, of a different type, that facilitates removal plus provides protection against moisture. Besides, robots and DIYers can mess up the application of anti-seize paste. Can't fire a robot.

On second thought, what does NGK know about spark plugs anyway. They only need to last for 60 days.

 

A digital guy in an analogue world ...

 

Are we overthinking this just a bit? Use or don't use, your choice.
I use it on plugs and believe I'm reducing the risk of a seized plug or one that rips the threads right out of the head, which is exactly what happened to my brand new, 10 hr in-service Loncin pressure washer motor when I pulled the plug to vacate the hydro-locked piece of junk. The dealer who took it back didn't even seem surprised!!
FWIW, the last coil I replaced was way back when, on my '69 Fargo van.

 

I don’t really care what autolite, NGK or others say, they will not be the ones dealing with stripped threads or broken plugs. All their statements and recommendations are to protect their interests and provide zero liability. Like I mentioned before, all it takes is that one plug to throw all these theories and “professional” advice out the window.

 

If over torquing is a primary driver of broken and warranty claimed plugs, suppliers will definitely say not to use anti-seize. It lubricates the joint and amplifies clamp load and stretch for any given torque level.

 

Autolite Video:

I missed the application of anti-seize in the video.

As I understand it:

Plated spark plugs = no anti-seize unless reused (plating compromised). Plated plugs have a shiny finish on the threads

Unplated spark plugs = anti-seize. Unplated plated plugs have a raw, non shiny finish on the threads. Not likely for aluminum heads though. Aluminum heads get the special plated treatment.

Anti-seize, motor oil, maybe even maple syrup have been used on spark plugs for years without concern about conductivity. I don't believe there is a concern today either.

 

Autolite Video:

I missed the application of anti-seize in the video.

As I understand it:

Plated spark plugs = no anti-seize unless reused (plating compromised). Plated plugs have a shiny finish on the threads

Unplated spark plugs = anti-seize. Unplated plated plugs have a raw, non shiny finish on the threads. Not likely for aluminum heads though. Aluminum heads get the special plated treatment.

Anti-seize, motor oil, maybe even maple syrup have been used on spark plugs for years without concern about conductivity. I don't believe there is a concern today either.

And he did not even need a torque wrench.


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Look at Permatex antiseize — it’s a mixture of copper, aluminum, and graphite.

But that doesn’t really matter, anyway. 10 or 15 kV doesn’t really care about a small amount of resistance. Take a plug out and hold it away from something metal. Crank the engine. The spark will easily jump both gaps — the one on the plug and the one from plug to ground. There’s nothing special about the ground side of a circuit that requires very low resistance.

 

I've always used a little bit of anti-seize on the spark plugs of every vehicle I've changed them. Never had an issue removing the plugs tens of thousands of miles later, or had an ignition issue related to the plugs. It doesn't take much to coat all of the threads lightly.

 

All it takes is one incident to turn what would otherwise be routine maintenance into an expensive repair and long downtime. No spark plug or car manufacturer will come to your rescue, despite all their claims high tech coatings.

The real reason anti-seize is not recommended is simply because it’s extremely hard to control how much an individual will use it. The meaning of “little” differs from one person to another. The level of experience and competence is also a huge factor. It is simply not worth it to the companies to recommend this because the liability is too great with no benefit to them.

 

Sure, the manual doesn't spec an anti-seize but then they don't care about engines outside of the warranty period and expect owners to change plugs regularly. I don't change mine very often, on the current '05 3.3 I went something like 230,000km(+/-) before they were changed from the plugs installed at the factory. Never a misfire that wasn't caused by oil on the plug boot of one cylinder (cleaned up, no more misfire) and zero change in fuel economy with the new plugs. The gap was about 1.8 x spec, if I recall correctly. There are a heck of a lot of perfectly serviceable plugs clogging our land fills.
I use a very small amt of never seize whenever I change plugs....basically put a little on, then try and remove the majority, leaving just the lightest trace amt. Few things scare me more than removing very old plugs from awkward locations. I recently changed out a set on a Ford 460 iron head, plugs that hadn't seen the light of day in 34 years and it would have meant scrapping the motorhome if one had broken off, believe me!

 

The gap was about 1.8 x spec, if I recall correctly.

This isn’t very good for ignition secondary components like plug wires and coils. Modern coils will likely be capable of putting out enough voltage to fire plugs consistently with gaps this wide, but that high voltage is trying to find easier paths to ground, and that means it’s trying to go through the insulation on plug wires and coils. This can and will damage them.

 

Thanks for the info. I’ll keep that in mind when it’s time to replace the spark plugs on my van.

 

Just as I thought, the manual has no mention of it, so it is not used. 14ft/lbs that's it.

 

There's some that don't want to acknowledge that.

I don't even use anti-seize on my lawnmowers and snowblower.

 

Interesting article here re anti-seize (copper for high heat):

How to Change Your Spark Plugs & Why You Shouldn't Use Copper Grease

Spark Plug threads - To grease or not to grease, that is the big question. Click here for the answer and the common copper grease myth busted.

www.driven2automotive.com

In Our Experience
For NGK warranty purposes, we have to ship all damaged spark plugs back to NGK UK so that they can be officially examined and documented. As of now, it turns out 100% of the spark plugs in the last 5 years that were returned due to thread breakage were the result of customers using thread compound, or simply over tightening them. The NGK warranty reports are always compiled with detailed photographs pinpointing the exact reasons for failure, even to the very smallest of details such as hex swelling and magnified photos are taken and recorded.

But I Know a Mechanic Who Always Uses it on Spark Plugs?
Don't we all.

If your mechanic uses copper grease on spark plug threads well as torquing them down, then be warned! NGK is adamant this procedure should be avoided on all costs. We must remember that the spark plug manufacturers are the most experienced out of all of us, with millions of pounds spent on R&D and hundreds of qualified mechanics testing them day in, day out.

Copper is the higher heat anti-seize. Case closed on using anti-seize, don't you think?

I have about 2750 engine hours on the OE spark plugs in my 2016 DGC now. They say Iridium are good for 3000 to 4000 engine hours depending on quality of gasoline used. I run about 150 to 160 engine hours per oil change. So, they are good for another oil change or two.

 

Great advice until one (spark plug) breaks off inside your block - invariably, it is the one that is hardest to reach or get a tool on..

 

I've always used it on all my vehicles without a problem, be it used or brand new spark plugs. I use the silver aluminum kind.

At work assembling new snowmobile and ATV engines, we use NGK spark plugs into aluminum heads and don't use any antiseize. I don't know how it works out for the customers in the long run, but maybe the plugs get changed out more often so it doesn't matter.

 

No anti-seize on spark plugs ever, any engine. It interferes with the electrical connection to the block resulting in a weaker spark.

 

Perhaps you meant ground. If so, it’s true a ground is needed, however there is no interference if you apply anti seize as you claim. Otherwise dialectic grease could not be used either on any electrical connection.
Why does it work? Because as the spark plug is torqued, the side of the threads that have load on them, will squeeze out any lubricant and have metal on metal contact. The lubricant will migrate to the unloaded side of the threads because there is a small gap there, where otherwise soot and other combustion by products would eventually go into. That’s the basic principle of how anti seize helps prevent stuck plugs, by blocking the entryway and providing lubrication during removal.