I’m not the original owner of my 2012 XJL so I don’t know for sure if my Spark plugs have ever been replaced but I find it doubtful.
I have 67,000 miles on her and would like to know what the thoughts are about replacing them at this time or wait until there’s more miles.
Purrs like a kitten now with no issues just want to keep it that way.
Any input would be appreciated.

 

To the best of my knowledge, spark plugs on the 5.0 L engine are not scheduled for replacement until you have 100k miles on the odometer. But, to be sure, check your owners manual. If you don't have one you can download one from the stickies section at the top of the X351 Forum first page.

 

Yep, not "due" for replacement until 100k miles but even that is a little conservative, they are NGK Iridium plugs which last forever and you can probably get 150k miles out them.
If it ain't broke don't fix it!

 

I have to agree with the above too. I have changed several late model Jaguars plugs out at 100K miles or more and have never noticed any changes and the old plugs looked just fine. I do see the plug gaps opening up some with more miles.
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Oz , my current jaguar is a v6 autobiography petrol , only one of 7 in the Uk , on the osh it had the spark plugs changed at silly miles of 4-6 000, I am now on 19,000 miles in your valued opinion should I forget all about changing them to say the 100,000 mark , ? I also had the same car as yourself a ftype v6 380 ps and it had the spark plugs changed twice as jaguar recommended, probably not needed , prior to that had an 5 litre xkr that the plugs only needed changing at the 100 k Mark . Cutting it short would I be wasting money , car runs sweet . George05

 

Yes you would be wasting your money (and time) to have the spark plugs changed again at only some 14,000 miles since the last change, especially at the exorbitant rate charged by a JLR dealership.
On my F-Type V6 (same engine as your XJ) the spark plugs are still the originals at now nearly 73,000 km, with the last approx 40,000 km with a larger crank pulley and VAP tune, and the engine still runs sweet as a nut with zero indication that the spark plugs need replacing. I don't plan on replacing the spark plugs for many years if ever as I only do some 8,000 km/year these days.

 

Thanks OZ , Iam now retired and only do low miles per year so will hold off .

 

I did have one fail around the 100k mark, shattered in the recess. Was a delicate extraction. an original NGK too.

 

If the plugs aren't too hard to get at, I'd suggest removing them and applying a small dab of anti-seize compound to them, as well as a little dielectric grease to the boots, just so the plugs don't weld themselves to the cylinder heads, and the boots to the plugs.

 

I i like to change at 50,000 miles. 1) it keeps the threads from freezing in the bores, 2) it lets you 'read' the plugs for unusual cylinder wear/rings and 3) it lets you check gap for variation.

 

On the AJ133/126, I'd be more concerned with keeping the high-pressure fuel injectors from becoming clogged, which is quite common.

As others have said above, the spark plugs seem to perform well even beyond the recommended service interval.

 

One more tip is to get the engine warm before trying to remove the plugs.
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