Changed my plugs after 38k (PICS)

[auxmike]

Car left the factory with NGK, Toyota dealers sell DENSO replacements. Car seems to run a LOT better now. I don't care what they claim, I ain't leaving my plugs in for 100K.:bellyroll:
NOTES:
1)The factory plugs I removed are covered with what appears to be sticky cosmoline on the threads, like the stuff they rub down old military rifles with! That's what it smells and looks like.... It's NOT motor oil.
2)There appears to be a "pad" attached to the inside of the hook part of the plug across from the iridium center electrode. Never seen that on any other plug before.
3)The iridium is like a pin tip, hard,brittle and delicate.
$38 shipped Priority mail from Covina Toyota in Cali via Ebay....
The pics are from a Blackberry, so please excuse the quality.:redface:

[nemelek]

Were they easy to change?

[auxmike]

You need a 10mm socket to remove the engine cover bolts (4) first.
Under there you will see the four coil packs that are held down by another four 10mm bolts. You would need to unplug the connectors first. After that the coil pack pulls out and the hole in the valve cover is exposed, that's where the plug is. A 5/8 spark plug deep socket is needed to get the plug out.
After installing the plugs, a torque wrench is required to properly tighten them.
To answer the question, no it's not hard to do IF you have the right tools and know how/confidence.:biggrin:

[Hershey]

Agree with 100,000 miles seems too much . I'll usually get the iridiums changed at 70,000 > 80,000 miles . Did so with a 2000 Corolla and the fuel economy got bumped up a bit . Think they were NGK . Let us know if you get any increase in gas mileage . Don't do plugs for aluminum blocks , the old cast iron yes . Thanks for the post .

[Hershey]

Did you ever use CHEVRON Techron or SHELL V-Power for F.I. / fuel system cleaner before the change ? How did the plug for the #1 cylinder look ? Any different than the others ? All seem to be in same condition .

[daddyo]

Did my 08 sedan (52k) two weeks ago and the plugs were identical save for the screws which only had black carbon looking build-up on the half closest to the tip.
Same result as you though- Much, much smoother ride and far better acceleration.

[marcus]

Make sure u guys check the spark plug gap still

by the way I think denso only last 30k miles vs ngk iridium 120k miles

[big lo]

NGK sparks are way better than the Denso spark plugs, nice write up Aux, I changed mine when she had 25000, and again when she hit 50000, soon to be changed again lol

[Astroman]

What is the proper gap? I'm 95k miles on the OEM setup and need to start thinking about these things.

[Bluevitz-rs]

hopefully you used some sort of anti-seize on the threads, or come next time you change them they might be "welded" to the head. The metal in the spark plugs tends to react with the aluminum in the head causing them to bond together.

[swidd]

The stock ones I replaced at 86,000 were "welded" pretty good, and had almost rust-like bond to the cylinder head. I also achieved much better acceleration and cold start with new plugs, and it seems it bumped my MPG a little too.

[marcus]

What is the proper gap? I'm 95k miles on the OEM setup and need to start thinking about these things.

1-1.1 mm or .039-.043 inch

[Hershey]

Years ago , would set the plugs to 0.40 for TOYOTA engines .

[Lil Abner]

I'm pretty sure you don't gap Iridium plugs! It will damage the electrode and pad.

[auxmike]

Did you ever use CHEVRON Techron or SHELL V-Power for F.I. / fuel system cleaner before the change ? How did the plug for the #1 cylinder look ? Any different than the others ? All seem to be in same condition .

Never used any Techron, etc. all the plugs look as pictured, the same.

[auxmike]

Did my 08 sedan (52k) two weeks ago and the plugs were identical save for the screws which only had black carbon looking build-up on the half closest to the tip.
Same result as you though- Much, much smoother ride and far better acceleration.

Yeah, it DOES really make a difference! Worth doing...:tongue:

[auxmike]

hopefully you used some sort of anti-seize on the threads, or come next time you change them they might be "welded" to the head. The metal in the spark plugs tends to react with the aluminum in the head causing them to bond together.

I put a little Mobil 1 on the threads before installing. I'm sure there's still plenty of that cosmoline stuff stuck inside the hole threads.

[auxmike]

I'm pretty sure you don't gap Iridium plugs! It will damage the electrode and pad.

Sparkplugs.com states .044 for most of these Yaris fitments. I did'nt have a guage that went that big, but a .040 slid through without dragging.
I too was'nt planning on gapping the pin tip like electrode!:eek:

[auxmike]

NGK sparks are way better than the Denso spark plugs, nice write up Aux, I changed mine when she had 25000, and again when she hit 50000, soon to be changed again lol

I did'nt choose either brand, I just ordered the dealer parts and a DENSO is what I found in the box.:iono:
NGK are all Japan made, DENSO are a mix of Japan/USA parts, see box pic...

[auxmike]

Make sure u guys check the spark plug gap still

by the way I think denso only last 30k miles vs ngk iridium 120k miles

Not true.
DENSO sells two types of iridium plugs;

IK16 is the "regular" Iridium plug you're writing of.

SK16R11 is the "long life" Iridium OEM replacement part they market that the dealer sold me.

[RedRide]

Denso make a performance and long life iridium plugs.

The difference with the perfomance plug it that it has a grove in the side electrode that is supposed to concentrate the spark and give a slighly better prerformance during rapid acceleration.
This groove is eroded away after about 30k miles and although the plug is still very servicable, the benefits of the groove are no longer present but, they wiil stiil perform like a standard iridium plug. This is why they say to replace them after about 30k.

I used the Denson performance plugs (IK16) in my Celica and they do seem to run slighty better. It's nothing dramatic however as it only a spark plug.
If you are going to change them at about 30-40 k miles anyway, you might as well go for go for the performance plugs.

BTW, I agree that 100k is way to long to change the plugs and most mechanics recomend at least pulling them out at 50k to inspect them and to prevent at them from seizing at the threads
So, if you are giong to pull them anyway you might as will replace them.

[johnny_vitz]

I'm pretty sure you don't gap Iridium plugs!

^^ x10 - Definitely don't gap iridium or platinum tip plugs

[auxmike]

I put them in as they came from the box.
I can't imagine dealer techs messing with a gapper with a lot full of cars to be serviced...:confused:

[RedRide]

You can gap an iridium plug. The problem is the genter iridium electrode can be easily broken if your not careful.

From NGK:
"These plugs are made to the most popular gap sizes. In case it is necessary to re-gap these plugs, carefully open the ground electrode using a pair of needle-nose pliers or a wire style gap tool. Do not use a gap wheel type tool that will pry against the center electrode and could possibly break it off."

In other words, just be careful and don't put any pressure on the center electrode.

[johnny_vitz]

It is highly recommended not to by most manufacturers. I know you CAN, but it is more likely you'll damage it then set the proper gap. They almost all come with the exact gap your engine needs (vehicle specific applications). I've been told by our NGK rep not to gap them

[RedRide]

It is highly recommended not to by most manufacturers. I know you CAN, but it is more likely you'll damage it then set the proper gap. They almost all come with the exact gap your engine needs (vehicle specific applications). I've been told by our NGK rep not to gap them

Yes, manufactures tell people not to gap them because they know there are many idiots out there who wont heed their advise about the center iridium electrode or may not even be aware of it.

In addition, the ground electrode is not iridium and will erode as quickly as most any other high quality plug. Remember the electrode wear on the performance plug?
Also, it is always prudent to check the gap on any new plug as there is always a possibility that one may not be set to specs.

You can't damage the plug unless you go in there like a bull in a china shop and ignore the warning about the center elrctrode. Remember the electrode is sturdy enought to withstand all the explosions for 100k miles.

[marcus]

wow toyota canada seem to switch to denso no more ngk sparks plug on toyota system friend just checked it..

[fnkngrv]

Wonder how the difference would be noticed if at all on a boosted motor...

[BLAZINBLUEVITZ]

looks like plug change at 43,000 miles is coming up....

[Yaristeve]

NGK sparks are way better than the Denso spark plugs,

Since you broached the subject, why is NGK better than Denso? In fact, I've always wondered why people say one company's plugs are better than another? To me, plugs are like rocks; very simple. They just consist of an electrode, insulator, and a gap.

I use standard resistor Densos in my 1988 Toyota Pickup. The truck has 180k miles on it and it is on its third set of plugs. The first set lasted 100k and the second set lasted 70k. SUre the gap was something like 0.125" but otherthan lower gas mileage, the truck ran fine with 100k mile plugs in it...

I usually run just Densos in my Toyotas because that is what usually comes in them (I believe Denso and Toyota are related somehow).

[johnny_vitz]

NGK makes a quality plug for a good price. The only thing wrong with denso's most of the time (especially iridiums) is the price. The quality is there, they just want too much for them.

Wonder how the difference would be noticed if at all on a boosted motor...
You're better off using copper plugs when boosting

[Yaristeve]

NGK makes a quality plug for a good price. The only thing wrong with denso's most of the time (especially iridiums) is the price. The quality is there, they just want too much for them.

I can see how they're cheaper. Is that the only reason they're "better"?

Back in the day, the joke was, "NGK stands for No Good Kind". But, again, I never really saw how one plug could be better than another (for making power). I can see how quality might be different but then one would say, "xxx plugs are made better than yyy plugs."

Don't get me wrong; I am not defending Densos. I usually just walk into the dealership and ask for the right plugs and AFAIK, Toyota dealers always sells Densos.

[johnny_vitz]

Don't get me wrong; I am not defending Densos. I usually just walk into the dealership and ask for the right plugs and AFAIK, Toyota dealers always sells Densos.

I ran OEM denso plugs from the dealer until I boosted. I would recommend NGK for almost any import. I do not believe you make more power switching plugs, the only gain switching from copper plugs to platinum or iridium is the service interval (how long you can leave them in). There is no proof NGK is better than denso, it's just an opinion.

["G"]

Uhm ok? So what's the point of your post????? You changed your plugs and? I'm just trying to wrap my brain around your point?

Fyi denso and ngk make very good iridium plugs. You can't go wrong with either.

[auxmike]

I stuck with the OEM plugs since I figure the Toyota engineers used Iridium for a good reason besides service intervals...

[johnny_vitz]

There is no proof NGK is better than denso, it's just an opinion.

They are both good plugs...I answered his post...

[auxmike]

Uhm ok? So what's the point of your post????? You changed your plugs and? I'm just trying to wrap my brain around your point?

Fyi denso and ngk make very good iridium plugs. You can't go wrong with either.

If you mean me (the OP), I like to share pics and the procedure with other members to benefit the community overall. The "point" is to perhaps help others with my crappy pics and brainless thoughts about the experience of doing the job.
Are you "happy" now, can your brain start wrapping yet???:iono:

[Hershey]

Point is , the iridium is not a miracle plug , needs to be replaced sooner than 100,000 miles . Replace at what mileage you feel comfortable with by doing it yourself or a trusty mechanic . Have used N.G.K. in past TOYOTAs with good results . Like posted before , had the DENSO iridium in a 2000 COROLLA changed with NGK iridium ( bought at A.A.P. ) by a service center at around 75,000 miles ( give or take ) and the car ran better . Little more pep and small gain in gas mileage . Even the other 1/2 noticed it .

["G"]

Yes, now I understand your point and post. Basically a newb trying to help out other newbs who are just learning how to change their own plugs.

If you mean me (the OP), I like to share pics and the procedure with other members to benefit the community overall. The "point" is to perhaps help others with my crappy pics and brainless thoughts about the experience of doing the job.
Are you "happy" now, can your brain start wrapping yet???:iono:

[auxmike]

Yeah, that's it, you got it...really!:rolleyes:

[RedRide]

Toyota owns most of Denso and that's the reason why they use Denso plugs and other denso parts.

FWIW, My '02 Celica came stock with NGK plugs and they were perfectly fine.
I assume that Toyta used the NGK plugs whenerver there was a supply plroblem with the Denso plugs.
Personally, I do not know if they still use them.

["G"]

Dude they have not been a part of toyota for 62 years >> http://www.globaldenso.com/en/aboutdenso/history/index.html Denso and NGK both bid on contracts to supply all automakers with their product from the factory. Denso happened to win the yaris contract. Nothing to do with ownership but rather dollars and cents. Denso and NGk also private label their products for toyota and numerous other auto companies. That is why if you buy from the dealer some will have denso on the plug but a different part # which is usually the toyota part #. Denso will also assign a different part # to signify that it is a toyota private label plug.

[Focus_Sh1ft]

Wonder how the difference would be noticed if at all on a boosted motor...

The difference is whether or not you're going to have misfires under load. Gap is very important on an NA to FI engine. You can't just run the same gap spark plug.

[RedRide]

Dude they have not been a part of toyota for 62 years >> http://www.globaldenso.com/en/aboutdenso/history/index.html Denso and NGK both bid on contracts to supply all automakers with their product from the factory. Denso happened to win the yaris contract. Nothing to do with ownership but rather dollars and cents. Denso and NGk also private label their products for toyota and numerous other auto companies. That is why if you buy from the dealer some will have denso on the plug but a different part # which is usually the toyota part #. Denso will also assign a different part # to signify that it is a toyota private label plug.

Yes, they are an independent company and they must bid for Toyota contracts just like NGK, etc.
However, as I understand it, Toyota owns a large portion of Denso stock so, yes, Toyota owns part of Denso.

[special_k_828]

What are the torque values for the plugs?

[marcus]

13 lbs but some says 15 lbs

[marcus]

just an update on denso iridium gap from my research.

bigger gap vs stock which is normal and the iridium part of it will compensate for bigger gap..no need to adjust but you can..

[rl67pinoy]

OIL CHANGED EVERY 5K MILES
LUCAS F/I CLEANER EVERY 5K MILES
CHEVRON 92 OCTANE ONLY

["G"]

OIL CHANGED EVERY 5K MILES Not long enough per toyota.
LUCAS F/I CLEANER EVERY 5K MILES Not necessary.
CHEVRON 92 OCTANE ONLY Waste of money.

[Hershey]

Lookin' good .

[yaris2010RS]

what the hell happened to this thread? lol, it started out so nice......

very nice plugs at 120k, those can almost be put back in and used for a while longer.


on my moms camry which is at just shy of 300,000km its only on its second set of plugs, firs set wernt changed untill almost 190,000km. the random plugs i put in still look very good.

my way of thinking are, plugs are plugs, trolls are trolls :)

[BLAZINBLUEVITZ]

maybe its me BUt at 43k with a plug change car feels smoother throughout the gears and start up in the morning went from a 5-6 second crank to 2-3 seconds.....

[marcus]

I'm cranking 1-2 seconds 80k km

[swidd]

For smooth gears, spray the top of the gear box, the linkage, with WD-40. Smooth never tasted so smooth!

[BLAZINBLUEVITZ]

For smooth gears, spray the top of the gear box, the linkage, with WD-40. Smooth never tasted so smooth!

done that this weekend for the second time BUT i wasn't refering to shifting when i said smooth through the gears....

[RedRide]

Yes, an iridium plug will "last 100k miles.
However, why change them at 100k? Is 100k a magical milestone?

Any plug wiil deteriorate over it's life. Granted, an iridium pluge will deteriorate much more slowly but, it's still not the same as it was when new.

So, if your car is just a ocasional grocery getter, leave them in for 100k if you like
However, if you want to maintain top performance, change them more often.

["G"]

Exactly! ^^^

[bzinn 1]

Do not rely on that old anti seize left on head threads to work for the new plugs,always with aluminum heads put on new antiseize......or the next time it very well will be a head change needed when you break off the plug trying to get it out.....been there done that.

["G"]

Anti seize really is not necessary since the plugs have a trivalent coating on the threads. If they seize it's because they were overtightened. Also here is a link for the newbs >> http://www.ngk-elearning.com/

[Hershey]

Remove / install plugs when engine has sat for awhile is one .

[ROCKLAND TOYOTA]

Yeah, it DOES really make a difference! Worth doing...:tongue:

i achieved same results!

[SKurj]

OIL CHANGED EVERY 5K MILES Not long enough per toyota.


Eh? Here in Canada oil change interval is 8000kms... close enough to 5k miles...

On the echo i always left it to 10,000kms and used synthetics, no issues.

In 258,000kms on the echo I changed plugs twice, always worked lovely, and I used iridiums. New Yaris with only 32k on it, likely has OEM plugs in it, I may change them up soon just for the hell of it.

[fj40dave]

Just ordered the:
Denso Iridium Long Life Plug 3324 SK16R11 .044"
(Original Equipment Manufacturer and/or Original Equipment Equivalent) $9.35/ea
from sparkplug.com

I have 90k on my originals....we'll see what difference there is when they get here and I get 'em installed.

I know my mileage is off....I'm at about 35/mpg when I used to be close to 40.


OK....they have been swapped out.
I put some anti-seize on 'em.....I always use anti-seize when I do plugs.....hate fishing out plug holes (helicoils or rethreading)...

["G"]

Not true.
DENSO sells two types of iridium plugs;

IK16 is the "regular" Iridium plug you're writing of.

SK16R11 is the "long life" Iridium OEM replacement part they market that the dealer sold me.

Wrong answer. ik16 is the iridium "POWER" plug and the one you want.
The ik16tt is the standard iridium.
The sk16r11 is the iridium long life.

https://i.postimg.cc/ncTyNP5j/IMG-3379.jpg (https://postimg.cc/qzhD3jp4)

https://i.postimg.cc/P5RB58dd/IMG-3380.jpg (https://postimg.cc/5X8PPyHr)

https://i.postimg.cc/BvPRLQvH/IMG-3381.jpg (https://postimg.cc/R39g2mKZ)

https://i.postimg.cc/pTN4Db97/IMG-3382.jpg (https://postimg.cc/PL4Sj7Qz)

[nortonfb]

Your 7 years late.
It's all in the timing,

["G"]

Nope, 7-year-old info needs to be updated. So when people search they are not reading outdated info.

[rayfloyd170]

Car left the factory with NGK, Toyota dealers sell DENSO replacements. Car seems to run a LOT better now. I don't care what they claim, I ain't leaving my plugs in for 100K.:bellyroll:
NOTES:
1)The factory plugs I removed are covered with what appears to be sticky cosmoline on the threads, like the stuff they rub down old military rifles with! That's what it smells and looks like.... It's NOT motor oil.
2)There appears to be a "pad" attached to the inside of the hook part of the plug across from the iridium center electrode. Never seen that on any other plug before.
3)The iridium is like a pin tip, hard,brittle and delicate.
$38 shipped Priority mail from Covina Toyota in Cali via Ebay....
The pics are from a Blackberry, so please excuse the quality.:redface:




My manual says to use 90919-01164 or Denso K16R-U11, can i use this iridium type SK16R11? will it make a difference?

[dogsridewith]

If wrong heat range, can get to looking like those nasty examples in photos above.

[myfirstyota]

I just go to the dealer. What they give you has to be right...no?

["G"]

Yes, incorrect heat range can make them look similar. These are the correct heat range, they just have a solid 100k on them. Yes, you can buy the standard oem plugs from the dealer, but they are overpriced re-badged denso anyway. Also, the dealer doesn't offer the top of the line model like the "POWER" plugs.

[mirageman]

Nope, 7-year-old info needs to be updated. So when people search they are not reading outdated info.

Hit the nail on the head. I am about to change mine out tonight and started reading this many-years-old post from the beginning. Maybe late answer for the original conversation, but not a late reply for this thread at all. Keep it all in one thread, otherwise we'll have a thousand threads.

[mirageman]

Well, at 101,000 miles, I changed out my oem spark plugs. Pictures look better than actual. I usually get 46-49mpg this time of year, and I have only been getting 44.5 at best this year. We'll see if the sparkplugs will help. First plug had lots of resistance when I was taking it out, I sighed, thinking I ripped out head threads, but was pleasantly surprised when it came out clean. Turns out (pun intended) I had overdone the anti-seize a few years ago on the spark plugs when I tested compression at like 18k miles (I reused the oems at that point) and it just was too gummy after all these miles. I vacuumed out each hole with a vinyl tube and the house vacuum.
I did not go with the oem iridiums. They were over $9 a piece. I found these at Advanceautoparts.com.

https://shop.advanceautoparts.com/p/ngk-v-power-spark-plug-6953/5531691-P

Their description online says they are "oem approved". Although they are rated for 30k miles of use as opposed to 100k, they are 1/4 of the price. Made in the USA with Japanese and domestic parts it says on the box. V-groove gimmick looks cool. The way I see it, changing these out 4 times will get me farther than the 100k, and I'm out the store door with 4 new ones for $8.40 with an online coupon! Plus if I get rid of this car before the next 100k miles, I'll be losing money on the iridiums. OEM on mine were Densos.

I feel nothing different. Starts and goes just like before. I did however do a resistance check on the new and old. 3 new spark plugs were just about 5,200 ohms, one of them was 4,820. I only was able to test one oem used one at 6,400 ohms, the others did not give a reading, I guess due to the carbon, I didn't bother trying too hard to clean the tips and get a reading. On each of the 4 oems, tips and ground straps were worn on one side only. Funny how the picture doesn't show that. I think only the good sides were facing the camera!

[mirageman]

Yay! 48.3 mpg highway, light throttle 60-68mph.... loving these cheap plugs!

[BIGTAZ351]

Well then, I have some "Updating" of my own...It was found incorrect to depend on NGK’s "trivalent coating" and not using anti-seize (my mechanic friends joke as “irrelevant coating”). It has been discovered in the mechanic world that it isn't as good for corrosion/seizure protection as once thought, especially on subsequent (after first factory installation) new plug installations, as can be seen in many of the removed plug photos you will have carbon in the plug and head threads, and that can/will cause seizure of the plug, if you don’t clean it off (not recommended as you dump that crap down on top of the piston and it can damage the cylinder walls) or add a small amount of anti-seize and torque them to the proper “lubed” torque spec. After the steel “coated” but not anti-seized plug has been installed and heated thousands of times in an aluminum head, and that heating/cooling causes the plug to microscopically “walk” in the head due to the dissimilar metal’s expansion rates, creating a carbon grinding action, which breaks down the coating, and allows corrosion of causes seizure. The plug manufacturers don’t want you to use anti-seize because not many people know how to de-rate the torque spec for installing the plugs. However, there are automotive manufactures that DO recommend using anti-seize, regardless of the plug mfr’s recommendations.

Just what I have learned from the Automotive and in the Power-Sports world, in the last 8 years…

I have always used Anti-Seize as taught to at the small engine mechanic shop I grew up in, but it was more a personal preference thing. (I even use it on lug nuts and other long-term attachments, never had a problem, EVER.)

I also change my plugs long before the 100,000 mile recommendation.

[bronsin]

The plugs went 150,000 miles in my wife’s Camry. The new ones didn’t make it run any better the old ones work just fine.

The accessory belt and 150,000 miles on it also before I change it. The gauge I got said it was not worn at all. I could nt Bear to throw it out.

[BIGTAZ351]

I have found going longer distances on plugs causes other problems that may or may not be apparent right away... In the old days it would burn rotor and cap due to excessive secondary resistance...NOW it causes coil packs to get hot and burn out, due to excessive secondary resistance...

I always keep the old belt in the back (along with a few tools to do the emergency change) but once they start drying out/squealing/cracking...time to kick it out, I would rather NOT have it crap out along side the road, because I was too cheap/lazy to do preventative maint.

["G"]

I have never had an issue not using anti-seize on plugs. My Yaris has 300k on it. I'm on my 2nd set of Denso Iridium power plugs. Oem plugs I took out at 100k. Installed the first set of Denso's and took them out at 200k. No seizures yet. I've not used anti-seize once since my first spark plug job in 1992. Not one seizure on many of my platforms, 80's rx-7's, 90's rx-7,s, 90's supra, 90's Landcruiser, 90's Toyota pickups, 90's dsm's, 2006 merc amg's, mitsu gvr4's, Cressida, 90's skyline gtr, Lancia Integrale, 2004 Mitsu Evo, the list goes on. You do not need it. It also reduces the sparkplug grounding connection.

[BIGTAZ351]

Well, To each their own.
I have been using anti-seize on plugs for 35 years, and have had ZERO problems, I would strongly disagree with the theory that it inhibits grounding of the plugs...My Ohm Meter also disagrees.
I am just stating what works well for me... And Preventative Maintenance is better than a tow bill.

[Leegamer]

I have found going longer distances on plugs causes other problems that may or may not be apparent right away...

Can you elaborate?

Just hit 175k miles on my original plugs. Car still seems to drive the same and get the same gas mileage so I haven't bothered changing them.

[mik36]

I am in same dilemma

I have DENSO SC16HR11

https://www.yarisworld.com/forums/showthread.php?t=63470

Looking to replace

I viewed with techstream misfire on cylinder 1

IS NGK is better than DENSO ?

[bronsin]

I changed the spark plugs on my wife’s 2005 Camry at 150,000 miles and they looked perfect in the car ran perfect also. I think it was $40 for the iridium plugs.

Totally unnecessaryIn my opinion. But I would recommend removing the plugs so they don’t become seized. I would say 50,000 miles to remove and reinstall plugs is a good idea. I think I also put anti-seize on the new plugs I put in. If the plugs seas and you stripped them removing them that wouldn’t be good.