hi guys this is my first post and was wondering what the best spark plug for my jag xjr 4.0 v8 supercharged 1997 x308 thank you

 

NGK BKR6EIX-11.

From Jaguar Documentation
Spark Plug Installation.
Apply 'Neverseez' to the 3-4 threads next to the spark plug electrodes. Fill to full thread depth for 180 degrees of thread circumference.
A CAUTION: Do not contaminate the spark plug electrodes.
Torque spark plugs to 25-29Nm (18.5-21Ib).

 

NGK - IFR5N10 For Supercharged 4.0lt engines, the 10 at the end of the part number is the gap = 1mm

 

I researched the plug issue a few months ago but since it's been brought up again here, could someone please clarify something for me?

I bought a 2001 XJ8 with 94,000 miles that had been fitted with a 1999 engine that had 41,000 miles. I diligently went to work insuring the car was in good shape (new tensioners, water pump, part load breather hose, thermostat along with aluminum housing, accessory belt, oil change with pan cleaning and new gasket etc etc etc.). The plugs that came out were the NGK - IFR5N10. Since the engine had only 41k miles I figured that's what Jaguar put in at the factory; I replaced with new plugs of the same type.

In my research on here, that's not what everyone recommends. In fact the previous poster in this thread states that that plug is actually for the supercharged engine, which mine is not.

So, are these plugs correct for my car or should I replace them with NGK BKR6EIX-11?

Thanks

 

The L6 (strait 6) used NGK 5 heat range. The AJ8 (AJ26) used 6 heat range. If the plug condition shows dark black insulators and it's a 5 heat range, 5 is too cold. If using a 6 and it's blistered, 6 is too hot and you drop to a 5. Originally equipped with Platinum plugs, the Iridium plug is an upgrade.

 

so, I am getting all different answers around here. so let me just ask for my own car . what is the best plugs for the 2000 XJR

 

I have been wondering this myself as I have a 1998 XJR...only thing I found was for XJ8 according to sparkplugs.com

NGK 2341 PFR6G-13E Laser Platinum Plug
NGK 3764 BKR6EIX-11 IX Iridium Plug

Those two supposedly. The iridium is an upgrade. Platinum is the stocker.

 

The ones Jag installed at the factory. Contrary to marketing hype, fancy aftermarket plugs will make no difference.