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Correct spark plugs are listed on the Specifications page in the back of the Owner's Manual.
The engine doesn't care what exotic metal is used nor are you likely to wear out the plugs since they have a 100,000 mile replacement schedule. I've not seen any reason to differ from the OEM spec.
PFR7G-11S or
PK22PR-L11S
are standard.
They come pre-gapped (that's the 11 in the part numbers) and with special coatings on the threads. Don't mess with the gap. Don't add anti-seize as it messes with the torque which was updated to 24lb-ft about 10 years ago. 1/4" or 3/8" torque wrench is invaluable.
I have removed my NGKs super deluxe spark plugs for valve adjustment/ checks. The plugs looked pretty good and as I could not find anything about using anti seize on re-used NGK plugs with Trivalent Chromate, I simply popped them in again dry using Billman’s increased torque value.
I installed new plugs along with my original valve adjustment around 40K miles if I recall correctly. I was suffering from the DBW tight valve syndrome. I wanted to double check at 65K miles and the valves were unchanged. (Good news!) I just reinserted the relatively new NGK plugs dry as I mentioned.
Some things I found on the NGK websites.
The only thing that was really new to me was reducing torque 20% when using anti seize.
This is from an NGK pdf that I can't seem to find rn:
Topic
The use of anti-seize compounds on spark plug threads that have a "special shell
plating" (i.e. Trivalent coating).
Issue
Applying anti-seize to the treads of spark plugs that have a special metal plating
thus allowing the installer to mistakenly over-torque the spark plug in the cylinderhead.
Over-torque stretches the metal between the last thread and the seal
between the cylinder head and spark plug, causing a much higher probability that
the spark plug will either break during installation or upon removal.
Solution
For spark plugs with special metal plating; do not use anti-seize on the initial
installation. If a spark plug with special metal plating is removed and re-installed,
only then should anti-seize be used prior to "re-installation".
Additional Information
It is recommended to use spark plugs with the special plating on all aluminum
cylinder head applications to prevent damage to the cylinder head.
The shell plating acts as a "lubricant" which breaks away from the main body of the sparkplug during removal thus preventing the bonding of the aluminum from the
cylinder head to the threads.
All NGK Spark Plugs are manufactured with special shell plating on the metal body.
The use of anti-seize on spark plugs is only recommended on those brands that do not offer a special metal shell plating. Spark plugs that have a shiny silver appearance on the metal body usually indicate that the spark plug is manufactured with special metal shell plating. All spark plugs that have a blackened or dull appearance on the metal body offer no protection against seizing or protection against bonding to the aluminum cylinder head.
The only thing that was really new to me was reducing torque 20% when using anti seize.
Actually, the website says the opposite. They are saying that using antisieze would require you to increase torque by up to 20% which may take you outside the safe torque use range for the plug. Antisieze will lubricate the threads. However, Billman250's research showed that there appears to be plenty of torque headroom on the OEM NGKs. But like NGK states, most new plug failures they see are related to over torque situations.
Actually, the website says the opposite. They are saying that using antisieze would require you to increase torque by up to 20% which may take you outside the safe torque use range for the plug. Antisieze will lubricate the threads. However, Billman250's research showed that there appears to be plenty of torque headroom on the OEM NGKs. But like NGK states, most new plug failures they see are related to over torque situations.
Give that a re-read. What folks are discussing above is accurate. If you use anti-seize and use the OEM recommended torque value, you are actually going to apply MORE force to the plug/threads than desired. So in this case, you would want to reduce your torque wrench target value by 20%.
I'm glad this topic came up as I was generally aware of the no anti-seize note from NGK, but not the reasons why.
