I have ran 100k or more miles on 8 occasions in 4 vehicles(Pontiac(twice), Ford(3 times), Jeep and my '06 S (twice).
The NGK's and Denso plugs have anti seize on the threads from the factory that keeps the plugs from welding to the head. Use them with confidence.

Rod

 

I change 100k plugs in modern Hondas a lot. a lot a lot. even here is the rust belt I've never had one give me issues. I've seen my fair share of messed up plug or coil situations but on the normal maintenance minder 4 its been fine.

 

The Densos had a big edge in the first watercooled Suzuki GSXR and are highly reccomended - at least here in germany - in the air cooled BMW boxer community. And if these guys tell you that something "Made in Japan" is good it is remarkable.

 

Yes, i know that there is a coating on the threads today . The manufactures should print this hint on the Boxes to end some Discussions. It just looks like a ordinary Zinc plated bolt to everybody.
I will use the higher torque numbers, thanks.

 

Thanks for all the helpful answers Gentleman!

 

Are you going any deeper into the head? Valve adjustment check? I was wondering how your gaskets were holding up on the spark plug tubes. I bought some new ones for a valve adjustment a couple of years ago, but the current OEM ones seemed to be in very good shape so I left them alone.

 

I did the last Valve adjustment check two years ago. The gaskets i used back then where from Victor Reinz and where a dissapointment, they leaked. The spark plug tube was filled with oil about 1/3. Engine run fine nevertheless, the ignition coils survived beside beeing soaked in Oil. I have installed OEM Honda gaskets now. I didn´t cheked them for leaking so far. My S2000 is in winter storage now. The Landlord of the garage dont like wrenching on cars in his garage. I will install the spark plugs in April when i could drive the car in my little shop.

 

little story time

so my neighbor the other day comes over and says hey can you look at my car its running very rough and the check engine light is flashing..... its a 2004 Toyota Camry 2.4. its got cylinder 3 misfire codes, so i swap the coils around to see if the code moves and sure thing it does. so i tell her. you should just do all 4 coils as they look original from 2004. i tell her we should also do the plugs as well if they have never been done. well come to find out they have NEVER BEEN DONE either lol. so me not thinking or asking how many miles are on the car i pull it into my driveway and look at the cluster... holy shit 384,511 miles!!!!!! So i go ask her again. are you sure these spark plugs have never been done? she said no never. only things that were ever done maintenance wise have been oil changes and transmission drain and fills and brakes. i said ok ill do them lol. im thinking to myself i hope these plugs come out lmfao... well did the job and those original DENSO plugs came right out no issues at all not even a squeak when taking them out. i was really surprised with that many miles lol. let me tell you though the gap on those plugs looked like the grand canyon ! NGK is my go to plug but nothing wrong with running densos. My s2k came with densos from the factory but i replaced them with NGK's

 

Hell of a story! Toyota vehicles from that era are really great.

 

One thing about the gap. If it's just a Iridium plug, with a standard ground electrode, the gap will increase as the ground electrode wears out. If it has a platinum ground electrode(with a Iridium or Platinum center electrode) the gap should stay the same even with 200k miles. I've seen this first hand, but just because the gap is the same doesn't mean the rest of the plug is still working like it should.
That said I have never had a Iridium plug go bad in 100k mile change intervals.

Rod