LR3 Iridium IX Spark Plugs

D4782

Observer
Hello all,

My spark plugs were due, and upon finding out that LR specs the NGK IFR5N10 (Laser Iridium) at over $20 CAD, I began some research. Many had warned against using anything but the NGK laser iridium. NGK, when using their database recommends the Laser IFR5N10 Iridium as OE Series, and the BKR5EIX-11 Iridium IX as an alternate replacement.

Their site ( https://www.ngksparkplugs.com/about...-difference-between-oe-iridium-and-iridium-ix) states that the OE series were designed for maximum longevity with a dual precious metal configuration and last 80-100 thousand miles. The NGK Iridium IX has a single precious metal configuration and last 40-50 thousand miles. Both are available in various heat ranges and applications, and "the two plugs perform similarly."

Many who have done the job have stated that they aren't comfortable leaving any plug in place for as long as 100,000 mi. as the plugs like to weld themselves in to the threads. I agree with that and plan on replacing plugs every 50 000 mi anyways so I was able to save over 50% of the Laser Iridium price by going with the Iridium IX. It has been a few thousand Km since and I have had no problems. I've noticed more even power in the low range, a smoother idle and lower fuel consumption.

The rest of my reading was of people on forums not sure if they should tackle the spark plug and wondering if it is an especially difficult job. Some recommended against even trying it. Well, I'm here to say that its plenty easy! An hour start to finish. A few tricks. Use a small pick to lightly pry up the plastic clip on the electrical connectors. As you hold the clip up use a flathead screwdriver to pop the plug off. Those plugs seemed to hold people up, but using this method I had them all off in a minute or two. The PCV doesnt need to be removed to do the replacement, however it does have to be off to properly install the plastic coil cover when you're finished so may as remove it at the start and get the extra room. Don't forget antiseize on the new plugs. Any lubricant or thread treatment will affect torque values, so follow the instructions on the NGK box. Hand tighten, then tighten an additional 1/2 to 2/3 of a turn.

Just wanted to pass along that the cheaper plugs work just fine!
 

DiscoDavis

Explorer
First, hats off and this is good info for those that might have a more timely maintenance interval in mind :) . Not many people have done write ups on these stateside. However,

Don't forget antiseize on the new plugs. Any lubricant or thread treatment will affect torque values, so follow the instructions on the NGK box. Hand tighten, then tighten an additional 1/2 to 2/3 of a turn.

Antiseize should NOT be used on spark plugs that are not the cast iron looking thread type. It absolutely affects the torque values and for this reason NGK used a plated coating on the threads (why they are silver in color) to standardize slip and account for the correct torque spec. If you use anti seize it will result in a bad torque value. FYI for anyone doing this job:

Did spark plugs on one last year

Note In some older threads, mention was made to anti-seize on the spark plug threads. This is NOT to be done on these plugs with this block. NGK put out some TSB a while back stating that the silver metal coating on the threads was meant to act as the lubricant, and if anti-seize is used, it messes up the torque value of the plug. Only if a plug is removed and put back then anti-seize can be used.

You will find this at the bottom of the post linked above.
 

Attachments

  • NGKSP-0907-1-Anti-SeizeonSparkPlugs.pdf
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D4782

Observer
Thanks for the info on antiseize! I didn't know about the coating meaning it wasn't required. I will be loosening and retorquing these right away then, as according to that info they should then be ok.
 

scott7022

Nobody
Great post and I'll echo the anti seize. Never done this on a discovery. I did have to do it twice on the SRT10 full-size Dodge. If you've ever done the drivers rear plug on a v10 Dodge and thought it was hard the Viper motor was at least twice that! Aluminum head and angled plug. Had to grind a thin wall deep socket just to do it incorrectly the first time!
 
Funny, I orderd the "Highly Recommended" plug kit from AB and they showed up in CHAMPION boxes with CHAMPION plugs.

Am I missing something?
 

TexasTJ

Climbing Nerd
I did the champions from AB too on our 06. Runs like a champ and they were the same plugs I pulled out.
 

TOUGE

Active member
I put BKR5EIX-11 in mine a few weeks ago and it runs fine, they were super cheap on Amazon. If you get any plug in the same heat range and the correct gap your shouldn't have a problem.

I have never used antiseize on any spark plug on any car I have owed but they all have been japanese alloy heads with either NGK or Denso plugs. Some of these cars have been track raced too and never had an issue install or removing them with out antiseize.
 

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