I have used copper anti-seize for years on Hyster & Yale with the 2.0 & 2.2 Mazda. I have never had a problem with it and the do not stick. Just my 2 cents on this topic. And thank you guys for all your input, this site is great.

yeah RCA, its a judgement call for the tech when removing them, any experienced tech will notice this right off and take precautionary measures and if he see's that its not happening with any positive results he should inform the customer of the situation and give him the option to make the decision. And yes its true in alot of cases its the same tech that usually deals with the truck again, i just threw that in there about a different tech because some dealerships tend to use the policy of making a 'quick response' to service calls and send out the first available tech.
In any case they (the customer) generally leave it up to the tech to make the call for them and they take the advise of the tech. But in any case i always keep a 14mm helicoil sparkplug kit onhand just in case ;o)

When i change plugs in these units, i will loosen them and feel for resistance when trying to back them. If any is felt, i will work the plug back and forth several times splitting the difference until plug feels loose. Using shop cloth or paper towels i will encase the insulators of the plugs and pack loosely against head. Then i liberally apply penetrant oil to paper towel/cloth until oil cannot be absorbed by cloth/towel anymore. Tell the customer i will be back the next day to remove plugs. If customer is bent on unit to be repaired pronto i will try to work them with some kind of wonder oil while attempting to wrench them out. But if plugs are stubborn and know it is pulling threads, i will simply grab my impact wrench, remove the plugs with the threads and install coils. I let the person paying for repairs decide if another day is worth it. Most of the time there is not enough threads left to chase and once they start pulling it compounds the further they back out. Thread chasing can be gotten away with when using the longer shanked plugs but forget it on the new designed plugs as you will not get torque specs most of the time and you will leave the next guy ( which is probably going to be you anyway) having to install coils.

i'm aware of the bulletins these mfg's put out on that but in any case I have used it I have never had any problems like they warn about ever.
it's a choice I made after my own experiences using antiseize and until I encounter evidence to the contrary that I see causing any damage to the plugs or the engine I will continue to use it.

Anti seize compound / grease shouldn't be used on plated spark plugs, NGK even put out a tech bulletin of the problems / damage that can happen when it is used.

Google: " NGK sparkplugs anti seize " if you want to read it / look at the pretty pictures.

yes edward they did say that but if applied correctly it works well, i've had no issues using it. And i have tried numerous times trying to 'ease' them out exactly the way kevin suggested even using pb blaster or another comparable penetrating oil only to have it wipe the threads out anyway. The damage it causes alters the torque capability of the threaded area and in just about every case i've done this you just cannot torque the plug properly without it starting to pull out the threads that are left.
Any other tech that may go out afterwards and change plugs will most certainly wind up stripping it the rest of the way out not knowing what had transpired beforehand and inevitably wind up helicoiling it in the end. But hey... if one is uncomfortable using antisieze just put a couple drops of oil on the threads, anything other than dry threads should help.

Actually Kevin [et al.], the factory says not to use anti-seize on the Nissan K21-K25 engine, it can cause 'cool spots' where heat transfer is not as it should be. but you are very correct about the correct plugs not sticking down into the head the way he plugs did on the 4gMitsu series engines which should have anti-seize on them as they do have a couple of threads that do stick down into the combustion chamber.

Thanks guys for all the help. I have noted this for the tech and we are all very thankful. Please let me know if there is anything that I may help y'all with.

The Nissan spark plug # that I posted is an updated plug for these engines,it has the last 2-3 threads removed so threads are not sticking down in the combustion chamber where they can get carbon build up on them.
as for taking them out work them out SLOWLY....when you start to feel some resistance....turn the plug back in and keep working it in and out like this until removed,I Also use PB Blaster to help. I then use a spark plug tap and chase the threads to straighten them back up. Also there should be no need to use anti seize as the threads are nickel plated on theses plugs,but you can if you want your choice.

kevin is right about the spark plugs setting this code but the part he mentions about the engine being cold or not when removing them i would not take as a precursor to just yanking them out without paying attention to how they come out even when the engine is cold. Pay close attention to how they feel when you start to pull them out. Sometimes carbon will build up around the end of the thread shank that is protruding out inside the head. Once this occurs it wont matter if the engine is hot or cold, once it starts wiping out the threads theres no way around it tearing the threads out other than pulling the head and trying to clean up the inside carbon buildup first before removing the plug(s). Cat had this issue and came up with a different spark plug that was a tad shorter.

Knowing this can happen i made it a point to keep me a 14mm spark plug helicoil kit handy just in case there was no other way. I also use antisieze compound on the threads when installing the new ones but even using that DO NOT let any get on the end of the threads, it will harden from the heat in the chamber and create the same scenario.

AFTER you change the plugs and you still get a E-27........check your coils,these k21/25 engines will run decent on 3 cylinders and you might not notice it except for lower power output. The way I check them is I start and run the engine,the one at a time I will unplug the connector from a coil a listen for a RPM drop in the engine,you will get a code E-34 doing this biput that can be cleared once finished.....if you find a coil that dosent drop the RPM's when it's unplugged the install a new one

Thanks Kevin.
You guys in here have always been great.

Code E-27 is for crankshaft position sensor error......BUT FIRST thing I would do is install a new set of spark plugs,especially if the ones in it have a lot of hours on them and are gapped to wide from wear.....AND DO NOT...I REPEAT!DO NOT use aftermarket spark plugs...us Nissan Part # 22401-FU42A....as you say the truck is running fine this is the FIRST place I would go to is the spark plugs....ALSO change them when the engine is STONE COLD,or you will be putting helicoils in the head as the threads will come out with the plugs.