I need to know what type of spark plugs are best for my '06 STR

 

NGK IFR5N10

They are pre-gapped, very delicate electrode, already have anti-seize so do not add any.

 

https://www.jaguarforums.com/forum/j...-aj-v8-176996/

 

I am totally into Denso TT Iridium - I put those (the correct model obviously) into pretty much all of my cars, except for the V12s - there was some kind of reason as to why that was not possible.

Anyway: TT means: Twin Tip - there is a tip on each side.

My 3L V6 S-Type wants IT20TT
Your STR wants Denso IK16TT

You find the full list of Denso TT plugs on:
https://www.denso.com.au/ignition
Scroll down to downloads on the right side and click DENSO TT SPARK PLUG CATALOGUE

 

Yep, stick with OEM spec!

 

denso pk20tt or ik20tt

ngk iridium ix are overpriced and the oe iridium can only be bought from the dealer.

 

As I wrote 2 days ago: As per Denso table (link attached above):

3L V6 S-Type wants IT20TT
STR wants Denso IK16TT

 

OE is the way to go and can be purchased on Amazon or any auto parts store

 

Per Jaguar NGK IFR5N10

 

sure if you don’t drive hard in hot places.

good luck finding the middle east plugs outside the jag or aston dealer

 

Amazon doesn't ship internationally?

Frankly, To each their own... the OP can install Champion Spark Plugs for all I care....

 

If I found the correct information on the net, the first TT spark plugs were introduced in 2009.
That would be 1 year AFTER they stopped producing the S-Type.
Obviously they could not specify TT spark plugs as OE spark plugs for that reason...

I - for one - to not refuse to accept improvements in technology...

 

the colder ifr6n10 and the 7 middle east market plugs are like $220 minimum from the dealer.

one step colder densos are like $40 for a box of 8 at most

 

If I had to compromise I'd do so with Denso, considering many other parts on our cars are denso branded...